Add nullability annotations to tests in core/spring-boot

See gh-47263

core/spring-boot/build.gradle

@@ -50,6 +50,8 @@ dependencies {
 	optional("org.yaml:snakeyaml")
 	optional("tools.jackson.core:jackson-databind")
 
+	testCompileOnly("com.google.code.findbugs:jsr305")
+
 	testFixturesCompileOnly(project(":test-support:spring-boot-test-support"))
 
 	testImplementation(project(":test-support:spring-boot-test-support"))
@@ -106,3 +108,7 @@ sourceSets {
 		}
 	}
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}

core/spring-boot/src/test/java/org/springframework/boot/BannerTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot;
 
 import java.io.PrintStream;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -49,7 +50,7 @@ import static org.mockito.Mockito.reset;
 @ExtendWith({ MockitoExtension.class, OutputCaptureExtension.class })
 class BannerTests {
 
-	private ConfigurableApplicationContext context;
+	private @Nullable ConfigurableApplicationContext context;
 
 	@AfterEach
 	void cleanUp() {
@@ -59,6 +60,7 @@ class BannerTests {
 	}
 
 	@Captor
+	@SuppressWarnings("NullAway.Init")
 	private ArgumentCaptor<Class<?>> sourceClassCaptor;
 
 	@Test
@@ -123,7 +125,7 @@ class BannerTests {
 	static class DummyBanner implements Banner {
 
 		@Override
-		public void printBanner(Environment environment, Class<?> sourceClass, PrintStream out) {
+		public void printBanner(Environment environment, @Nullable Class<?> sourceClass, PrintStream out) {
 			out.println("My Banner");
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/DefaultApplicationArgumentsTests.java

@@ -35,6 +35,7 @@ class DefaultApplicationArgumentsTests {
 	private static final String[] ARGS = new String[] { "--foo=bar", "--foo=baz", "--debug", "spring", "boot" };
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void argumentsMustNotBeNull() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new DefaultApplicationArguments((String[]) null))
 			.withMessageContaining("'args' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/ExitCodeGeneratorsTests.java

@@ -37,6 +37,7 @@ import static org.mockito.Mockito.withSettings;
 class ExitCodeGeneratorsTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void addAllWhenGeneratorsIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> {
 			List<ExitCodeGenerator> generators = null;
@@ -45,6 +46,7 @@ class ExitCodeGeneratorsTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void addWhenGeneratorIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ExitCodeGenerators().add(null))
 			.withMessageContaining("'generator' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/MockApplicationEnvironment.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.mock.env.MockEnvironment;
 
 /**
@@ -27,12 +29,12 @@ import org.springframework.mock.env.MockEnvironment;
 public class MockApplicationEnvironment extends MockEnvironment {
 
 	@Override
-	protected String doGetActiveProfilesProperty() {
+	protected @Nullable String doGetActiveProfilesProperty() {
 		return null;
 	}
 
 	@Override
-	protected String doGetDefaultProfilesProperty() {
+	protected @Nullable String doGetDefaultProfilesProperty() {
 		return null;
 	}
 

core/spring-boot/src/test/java/org/springframework/boot/OverrideSourcesTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -35,7 +36,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class OverrideSourcesTests {
 
-	private ConfigurableApplicationContext context;
+	private @Nullable ConfigurableApplicationContext context;
 
 	@AfterEach
 	void cleanUp() {

core/spring-boot/src/test/java/org/springframework/boot/ResourceBannerTests.java

@@ -22,6 +22,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -170,12 +171,12 @@ class ResourceBannerTests {
 		assertThat(banner).startsWith("banner bar");
 	}
 
-	private String printBanner(Resource resource, String bootVersion, String applicationVersion,
-			String applicationTitle) {
+	private String printBanner(Resource resource, @Nullable String bootVersion, @Nullable String applicationVersion,
+			@Nullable String applicationTitle) {
 		return printBanner(new MockResourceBanner(resource, bootVersion, applicationTitle), applicationVersion);
 	}
 
-	private String printBanner(ResourceBanner banner, String applicationVersion) {
+	private String printBanner(ResourceBanner banner, @Nullable String applicationVersion) {
 		MockEnvironment environment = new MockEnvironment();
 		if (applicationVersion != null) {
 			environment.setProperty("spring.application.version", applicationVersion);
@@ -189,23 +190,23 @@ class ResourceBannerTests {
 
 	static class MockResourceBanner extends ResourceBanner {
 
-		private final String bootVersion;
+		private final @Nullable String bootVersion;
 
-		private final String applicationTitle;
+		private final @Nullable String applicationTitle;
 
-		MockResourceBanner(Resource resource, String bootVersion, String applicationTitle) {
+		MockResourceBanner(Resource resource, @Nullable String bootVersion, @Nullable String applicationTitle) {
 			super(resource);
 			this.bootVersion = bootVersion;
 			this.applicationTitle = applicationTitle;
 		}
 
 		@Override
-		protected String getBootVersion() {
+		protected @Nullable String getBootVersion() {
 			return this.bootVersion;
 		}
 
 		@Override
-		protected String getApplicationTitle(Class<?> sourceClass) {
+		protected @Nullable String getApplicationTitle(@Nullable Class<?> sourceClass) {
 			return this.applicationTitle;
 		}
 
@@ -213,23 +214,23 @@ class ResourceBannerTests {
 
 	static class MutatingResourceBanner extends MockResourceBanner {
 
-		MutatingResourceBanner(Resource resource, String bootVersion, String applicationTitle) {
+		MutatingResourceBanner(Resource resource, String bootVersion, @Nullable String applicationTitle) {
 			super(resource, bootVersion, applicationTitle);
 		}
 
 		@Override
-		protected List<PropertyResolver> getPropertyResolvers(Environment environment, Class<?> sourceClass) {
+		protected List<PropertyResolver> getPropertyResolvers(Environment environment, @Nullable Class<?> sourceClass) {
 			List<PropertyResolver> resolvers = super.getPropertyResolvers(environment, sourceClass);
 			PropertyResolver resolver = new AbstractPropertyResolver() {
 
 				@Override
 				@SuppressWarnings("unchecked")
-				public <T> T getProperty(String key, Class<T> targetType) {
+				public <T> @Nullable T getProperty(String key, Class<T> targetType) {
 					return String.class.equals(targetType) ? (T) getPropertyAsRawString(key) : null;
 				}
 
 				@Override
-				protected String getPropertyAsRawString(String key) {
+				protected @Nullable String getPropertyAsRawString(String key) {
 					return ("foo".equals(key)) ? "bar" : null;
 				}
 

core/spring-boot/src/test/java/org/springframework/boot/SpringApplicationAotProcessorTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot;
 
 import java.nio.file.Path;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
@@ -101,7 +102,7 @@ class SpringApplicationAotProcessorTests {
 	@Configuration(proxyBeanMethods = false)
 	public static class SampleApplication {
 
-		public static String[] argsHolder;
+		public static String @Nullable [] argsHolder;
 
 		public static boolean postRunInvoked;
 

core/spring-boot/src/test/java/org/springframework/boot/SpringApplicationShutdownHookTests.java

@@ -25,6 +25,7 @@ import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.TimeUnit;
 
 import org.awaitility.Awaitility;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
 
@@ -152,6 +153,7 @@ class SpringApplicationShutdownHookTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void addHandlerActionWhenNullThrowsException() {
 		TestSpringApplicationShutdownHook shutdownHook = new TestSpringApplicationShutdownHook();
 		assertThatIllegalArgumentException().isThrownBy(() -> shutdownHook.getHandlers().add(null))
@@ -168,6 +170,7 @@ class SpringApplicationShutdownHookTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void removeHandlerActionWhenNullThrowsException() {
 		TestSpringApplicationShutdownHook shutdownHook = new TestSpringApplicationShutdownHook();
 		assertThatIllegalArgumentException().isThrownBy(() -> shutdownHook.getHandlers().remove(null))
@@ -244,15 +247,16 @@ class SpringApplicationShutdownHookTests {
 
 		private final List<Object> finished;
 
-		private final CountDownLatch closing;
+		private final @Nullable CountDownLatch closing;
 
-		private final CountDownLatch proceedWithClose;
+		private final @Nullable CountDownLatch proceedWithClose;
 
 		TestApplicationContext(List<Object> finished) {
 			this(finished, null, null);
 		}
 
-		TestApplicationContext(List<Object> finished, CountDownLatch closing, CountDownLatch proceedWithClose) {
+		TestApplicationContext(List<Object> finished, @Nullable CountDownLatch closing,
+				@Nullable CountDownLatch proceedWithClose) {
 			this.finished = finished;
 			this.closing = closing;
 			this.proceedWithClose = proceedWithClose;

core/spring-boot/src/test/java/org/springframework/boot/SpringApplicationTests.java

@@ -23,6 +23,7 @@ import java.util.HashMap;
 import java.util.LinkedHashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Properties;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -32,6 +33,7 @@ import java.util.function.Supplier;
 import jakarta.annotation.PostConstruct;
 import org.assertj.core.api.Condition;
 import org.awaitility.Awaitility;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -167,7 +169,7 @@ class SpringApplicationTests {
 
 	private String headlessProperty;
 
-	private ConfigurableApplicationContext context;
+	private @Nullable ConfigurableApplicationContext context;
 
 	private Environment getEnvironment() {
 		if (this.context != null) {
@@ -202,6 +204,8 @@ class SpringApplicationTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway")
+	// Test null check
 	void sourcesMustNotBeNull() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new SpringApplication((Class<?>[]) null).run())
 			.withMessageContaining("'primarySources' must not be null");
@@ -360,7 +364,9 @@ class SpringApplicationTests {
 		application.setWebApplicationType(WebApplicationType.NONE);
 		AtomicReference<ApplicationReadyEvent> reference = addListener(application, ApplicationReadyEvent.class);
 		this.context = application.run("--foo=bar");
-		assertThat(application).isSameAs(reference.get().getSpringApplication());
+		ApplicationReadyEvent event = reference.get();
+		assertThat(event).isNotNull();
+		assertThat(application).isSameAs(event.getSpringApplication());
 	}
 
 	@Test
@@ -369,7 +375,9 @@ class SpringApplicationTests {
 		application.setWebApplicationType(WebApplicationType.NONE);
 		AtomicReference<ContextRefreshedEvent> reference = addListener(application, ContextRefreshedEvent.class);
 		this.context = application.run("--foo=bar");
-		assertThat(this.context).isSameAs(reference.get().getApplicationContext());
+		ContextRefreshedEvent event = reference.get();
+		assertThat(event).isNotNull();
+		assertThat(this.context).isSameAs(event.getApplicationContext());
 		// Custom initializers do not switch off the defaults
 		assertThat(getEnvironment().getProperty("foo")).isEqualTo("bar");
 	}
@@ -487,6 +495,7 @@ class SpringApplicationTests {
 		assertThat(environment.getProperty("foo")).isEqualTo("bar");
 		CompositePropertySource composite = (CompositePropertySource) environment.getPropertySources()
 			.get("commandLineArgs");
+		assertThat(composite).isNotNull();
 		assertThat(composite.getPropertySources()).hasSize(2);
 		assertThat(composite.getPropertySources()).first()
 			.matches((source) -> source.getName().equals("springApplicationCommandLineArgs"),
@@ -878,8 +887,9 @@ class SpringApplicationTests {
 	@Test
 	void defaultCommandLineArgs() {
 		SpringApplication application = new SpringApplication(ExampleConfig.class);
-		application.setDefaultProperties(
-				StringUtils.splitArrayElementsIntoProperties(new String[] { "baz=", "bar=spam" }, "="));
+		Properties properties = StringUtils.splitArrayElementsIntoProperties(new String[] { "baz=", "bar=spam" }, "=");
+		assertThat(properties).isNotNull();
+		application.setDefaultProperties(properties);
 		application.setWebApplicationType(WebApplicationType.NONE);
 		this.context = application.run("--bar=foo", "bucket", "crap");
 		assertThat(this.context).isInstanceOf(AnnotationConfigApplicationContext.class);
@@ -936,7 +946,7 @@ class SpringApplicationTests {
 		this.context = application.run();
 		assertThat(events).hasAtLeastOneElementOfType(ApplicationPreparedEvent.class);
 		assertThat(events).hasAtLeastOneElementOfType(ContextRefreshedEvent.class);
-		verifyRegisteredListenerSuccessEvents();
+		verifyRegisteredListenerSuccessEvents(this.context);
 	}
 
 	@Test
@@ -949,12 +959,12 @@ class SpringApplicationTests {
 		this.context = application.run();
 		assertThat(events).hasAtLeastOneElementOfType(ApplicationPreparedEvent.class);
 		assertThat(events).hasAtLeastOneElementOfType(ContextRefreshedEvent.class);
-		verifyRegisteredListenerSuccessEvents();
+		verifyRegisteredListenerSuccessEvents(this.context);
 	}
 
 	@SuppressWarnings("unchecked")
-	private void verifyRegisteredListenerSuccessEvents() {
-		ApplicationListener<ApplicationEvent> listener = this.context.getBean("testApplicationListener",
+	private void verifyRegisteredListenerSuccessEvents(ConfigurableApplicationContext context) {
+		ApplicationListener<ApplicationEvent> listener = context.getBean("testApplicationListener",
 				ApplicationListener.class);
 		InOrder inOrder = Mockito.inOrder(listener);
 		then(listener).should(inOrder).onApplicationEvent(isA(ContextRefreshedEvent.class));
@@ -1224,9 +1234,11 @@ class SpringApplicationTests {
 		application.setWebApplicationType(WebApplicationType.NONE);
 		application.addBootstrapRegistryInitializer((bootstrapContext) -> {
 			bootstrapContext.register(String.class, InstanceSupplier.of("boot"));
-			bootstrapContext.addCloseListener((event) -> event.getApplicationContext()
-				.getBeanFactory()
-				.registerSingleton("test", event.getBootstrapContext().get(String.class)));
+			bootstrapContext.addCloseListener((event) -> {
+				String string = event.getBootstrapContext().get(String.class);
+				assertThat(string).isNotNull();
+				event.getApplicationContext().getBeanFactory().registerSingleton("test", string);
+			});
 		});
 		ConfigurableApplicationContext applicationContext = application.run();
 		assertThat(applicationContext.getBean("test")).isEqualTo("boot");
@@ -1272,8 +1284,9 @@ class SpringApplicationTests {
 			.map(ApplicationFailedEvent.class::cast)
 			.findFirst()
 			.get();
-		assertThat(SpringApplicationShutdownHookInstance.get())
-			.didNotRegisterApplicationContext(failure.getApplicationContext());
+		ConfigurableApplicationContext context = failure.getApplicationContext();
+		assertThat(context).isNotNull();
+		assertThat(SpringApplicationShutdownHookInstance.get()).didNotRegisterApplicationContext(context);
 	}
 
 	@Test
@@ -1283,6 +1296,7 @@ class SpringApplicationTests {
 		SpringApplicationRunListener runListener = mock(SpringApplicationRunListener.class);
 		SpringApplicationHook hook = (springApplication) -> runListener;
 		SpringApplication.withHook(hook, () -> this.context = application.run());
+		assertThat(this.context).isNotNull();
 		then(runListener).should().starting(any());
 		then(runListener).should().contextPrepared(this.context);
 		then(runListener).should().ready(eq(this.context), any());
@@ -1320,7 +1334,11 @@ class SpringApplicationTests {
 		SpringApplicationHook hook = (springApplication) -> runListener;
 		assertThatExceptionOfType(SpringApplication.AbandonedRunException.class)
 			.isThrownBy(() -> SpringApplication.withHook(hook, () -> application.run()))
-			.satisfies((ex) -> assertThat(ex.getApplicationContext().isRunning()).isFalse());
+			.satisfies((ex) -> {
+				ConfigurableApplicationContext context = ex.getApplicationContext();
+				assertThat(context).isNotNull();
+				assertThat(context.isRunning()).isFalse();
+			});
 		then(runListener).should().starting(any());
 		then(runListener).should().contextPrepared(any());
 		then(runListener).should(never()).ready(any(), any());
@@ -1389,7 +1407,10 @@ class SpringApplicationTests {
 			.with(SingleUseAdditionalConfig.class)
 			.run()
 			.getApplicationContext();
-		assertThatNoException().isThrownBy(() -> this.context.getBean(SingleUseAdditionalConfig.class));
+		assertThatNoException().isThrownBy(() -> {
+			assertThat(this.context).isNotNull();
+			this.context.getBean(SingleUseAdditionalConfig.class);
+		});
 	}
 
 	@Test
@@ -1540,7 +1561,7 @@ class SpringApplicationTests {
 
 	static class TestSpringApplication extends SpringApplication {
 
-		private BeanDefinitionLoader loader;
+		private @Nullable BeanDefinitionLoader loader;
 
 		private boolean useMockLoader;
 
@@ -1567,7 +1588,7 @@ class SpringApplicationTests {
 			return this.loader;
 		}
 
-		BeanDefinitionLoader getLoader() {
+		@Nullable BeanDefinitionLoader getLoader() {
 			return this.loader;
 		}
 
@@ -1855,6 +1876,7 @@ class SpringApplicationTests {
 
 		private final String[] expectedBefore;
 
+		@SuppressWarnings("NullAway.Init")
 		private ApplicationContext applicationContext;
 
 		private final int order;
@@ -1926,14 +1948,14 @@ class SpringApplicationTests {
 
 	static class ExitCodeListener implements ApplicationListener<ExitCodeEvent> {
 
-		private Integer exitCode;
+		private @Nullable Integer exitCode;
 
 		@Override
 		public void onApplicationEvent(ExitCodeEvent event) {
 			this.exitCode = event.getExitCode();
 		}
 
-		Integer getExitCode() {
+		@Nullable Integer getExitCode() {
 			return this.exitCode;
 		}
 
@@ -1971,7 +1993,9 @@ class SpringApplicationTests {
 
 		@SuppressWarnings("unchecked")
 		<E extends ApplicationEvent> E getEvent(Class<E> type) {
-			return (E) this.events.get(type).get(0);
+			List<ApplicationEvent> events = this.events.get(type);
+			assertThat(events).isNotNull();
+			return (E) events.get(0);
 		}
 
 	}

core/spring-boot/src/test/java/org/springframework/boot/StartupInfoLoggerTests.java

@@ -17,6 +17,7 @@
 package org.springframework.boot;
 
 import org.apache.commons.logging.Log;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -133,11 +134,11 @@ class StartupInfoLoggerTests {
 
 		private final long startTime = System.currentTimeMillis();
 
-		private final Long uptime;
+		private final @Nullable Long uptime;
 
 		private final String action;
 
-		TestStartup(Long uptime, String action) {
+		TestStartup(@Nullable Long uptime, String action) {
 			this.uptime = uptime;
 			this.action = action;
 			started();
@@ -149,7 +150,7 @@ class StartupInfoLoggerTests {
 		}
 
 		@Override
-		protected Long processUptime() {
+		protected @Nullable Long processUptime() {
 			return this.uptime;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/admin/SpringApplicationAdminMXBeanRegistrarTests.java

@@ -24,6 +24,7 @@ import javax.management.MBeanServer;
 import javax.management.MalformedObjectNameException;
 import javax.management.ObjectName;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -54,7 +55,7 @@ class SpringApplicationAdminMXBeanRegistrarTests {
 
 	private MBeanServer mBeanServer;
 
-	private ConfigurableApplicationContext context;
+	private @Nullable ConfigurableApplicationContext context;
 
 	@BeforeEach
 	void setup() {
@@ -90,15 +91,18 @@ class SpringApplicationAdminMXBeanRegistrarTests {
 		SpringApplicationAdminMXBeanRegistrar registrar = new SpringApplicationAdminMXBeanRegistrar(OBJECT_NAME);
 		ConfigurableApplicationContext context = mock(ConfigurableApplicationContext.class);
 		registrar.setApplicationContext(context);
-		registrar.onApplicationReadyEvent(new ApplicationReadyEvent(new SpringApplication(), null,
+		registrar.onApplicationReadyEvent(new ApplicationReadyEvent(new SpringApplication(), new String[0],
 				mock(ConfigurableApplicationContext.class), null));
 		assertThat(isApplicationReady(registrar)).isFalse();
-		registrar.onApplicationReadyEvent(new ApplicationReadyEvent(new SpringApplication(), null, context, null));
+		registrar
+			.onApplicationReadyEvent(new ApplicationReadyEvent(new SpringApplication(), new String[0], context, null));
 		assertThat(isApplicationReady(registrar)).isTrue();
 	}
 
 	private boolean isApplicationReady(SpringApplicationAdminMXBeanRegistrar registrar) {
-		return (Boolean) ReflectionTestUtils.getField(registrar, "ready");
+		Object field = ReflectionTestUtils.getField(registrar, "ready");
+		assertThat(field).isNotNull();
+		return (Boolean) field;
 	}
 
 	@Test

core/spring-boot/src/test/java/org/springframework/boot/availability/AvailabilityChangeEventTests.java

@@ -40,6 +40,7 @@ class AvailabilityChangeEventTests {
 	private final Object source = new Object();
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenStateIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new AvailabilityChangeEvent<>(this.source, null))
 			.withMessage("Payload must not be null");

core/spring-boot/src/test/java/org/springframework/boot/bootstrap/DefaultBootstrapContextTests.java

@@ -18,9 +18,11 @@ package org.springframework.boot.bootstrap;
 
 import java.io.IOException;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.function.Supplier;
 
 import org.assertj.core.api.AbstractAssert;
 import org.assertj.core.api.AssertProvider;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.bootstrap.BootstrapRegistry.InstanceSupplier;
@@ -34,6 +36,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.api.Assertions.assertThatIOException;
 import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException;
 import static org.assertj.core.api.Assertions.assertThatIllegalStateException;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link DefaultBootstrapContext}.
@@ -49,12 +52,14 @@ class DefaultBootstrapContextTests {
 	private final StaticApplicationContext applicationContext = new StaticApplicationContext();
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void registerWhenTypeIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> this.context.register(null, InstanceSupplier.of(1)))
 			.withMessage("'type' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void registerWhenRegistrationIsNullThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> this.context.register(Integer.class, null))
 			.withMessage("'instanceSupplier' must not be null");
@@ -206,20 +211,23 @@ class DefaultBootstrapContextTests {
 	@Test
 	void getOrElseSupplyWhenNoRegistrationReturnsSupplied() {
 		this.context.register(Number.class, InstanceSupplier.of(1));
-		assertThat(this.context.getOrElseSupply(Long.class, () -> -1L)).isEqualTo(-1);
+		Supplier<@Nullable Long> supplier = () -> -1L;
+		assertThat(this.context.getOrElseSupply(Long.class, supplier)).isEqualTo(-1);
 	}
 
 	@Test
 	void getOrElseSupplyWhenRegisteredAsNullReturnsNull() {
 		this.context.register(Number.class, InstanceSupplier.of(null));
-		assertThat(this.context.getOrElseSupply(Number.class, () -> -1L)).isNull();
+		Supplier<@Nullable Number> supplier = () -> -1L;
+		assertThat(this.context.getOrElseSupply(Number.class, supplier)).isNull();
 	}
 
 	@Test
 	void getOrElseSupplyCreatesOnlyOneInstance() {
 		this.context.register(Integer.class, InstanceSupplier.from(this.counter::getAndIncrement));
-		assertThat(this.context.getOrElseSupply(Integer.class, () -> -1)).isZero();
-		assertThat(this.context.getOrElseSupply(Integer.class, () -> -1)).isZero();
+		Supplier<@Nullable Integer> supplier = () -> -1;
+		assertThat(this.context.getOrElseSupply(Integer.class, supplier)).isZero();
+		assertThat(this.context.getOrElseSupply(Integer.class, supplier)).isZero();
 	}
 
 	@Test
@@ -265,14 +273,14 @@ class DefaultBootstrapContextTests {
 	void instanceSupplierGetScopeWhenNotConfiguredReturnsSingleton() {
 		InstanceSupplier<String> supplier = InstanceSupplier.of("test");
 		assertThat(supplier.getScope()).isEqualTo(Scope.SINGLETON);
-		assertThat(supplier.get(null)).isEqualTo("test");
+		assertThat(supplier.get(mock(BootstrapContext.class))).isEqualTo("test");
 	}
 
 	@Test
 	void instanceSupplierWithScopeChangesScope() {
 		InstanceSupplier<String> supplier = InstanceSupplier.of("test").withScope(Scope.PROTOTYPE);
 		assertThat(supplier.getScope()).isEqualTo(Scope.PROTOTYPE);
-		assertThat(supplier.get(null)).isEqualTo("test");
+		assertThat(supplier.get(mock(BootstrapContext.class))).isEqualTo("test");
 	}
 
 	private static final class TestCloseListener
@@ -280,9 +288,9 @@ class DefaultBootstrapContextTests {
 
 		private int called;
 
-		private BootstrapContext bootstrapContext;
+		private @Nullable BootstrapContext bootstrapContext;
 
-		private ConfigurableApplicationContext applicationContext;
+		private @Nullable ConfigurableApplicationContext applicationContext;
 
 		@Override
 		public void onApplicationEvent(BootstrapContextClosedEvent event) {

core/spring-boot/src/test/java/org/springframework/boot/builder/SpringApplicationBuilderTests.java

@@ -19,8 +19,10 @@ package org.springframework.boot.builder;
 import java.net.URL;
 import java.net.URLClassLoader;
 import java.util.Collections;
+import java.util.Properties;
 
 import org.assertj.core.api.InstanceOfAssertFactories;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -56,7 +58,7 @@ import static org.mockito.Mockito.spy;
  */
 class SpringApplicationBuilderTests {
 
-	private ConfigurableApplicationContext context;
+	private @Nullable ConfigurableApplicationContext context;
 
 	@AfterEach
 	void close() {
@@ -64,7 +66,7 @@ class SpringApplicationBuilderTests {
 		SpringApplicationShutdownHookInstance.reset();
 	}
 
-	private void close(ApplicationContext context) {
+	private void close(@Nullable ApplicationContext context) {
 		if (context != null) {
 			if (context instanceof ConfigurableApplicationContext configurableContext) {
 				configurableContext.close();
@@ -103,9 +105,11 @@ class SpringApplicationBuilderTests {
 
 	@Test
 	void propertiesAsProperties() {
+		Properties properties = StringUtils.splitArrayElementsIntoProperties(new String[] { "bar=foo" }, "=");
+		assertThat(properties).isNotNull();
 		SpringApplicationBuilder application = new SpringApplicationBuilder().sources(ExampleConfig.class)
 			.contextFactory(ApplicationContextFactory.ofContextClass(StaticApplicationContext.class))
-			.properties(StringUtils.splitArrayElementsIntoProperties(new String[] { "bar=foo" }, "="));
+			.properties(properties);
 		this.context = application.run();
 		assertThat(this.context.getEnvironment().getProperty("bar")).isEqualTo("foo");
 	}
@@ -140,8 +144,9 @@ class SpringApplicationBuilderTests {
 		then(((SpyApplicationContext) this.context).getApplicationContext()).should()
 			.setParent(any(ApplicationContext.class));
 		assertThat(SpringApplicationShutdownHookInstance.get()).didNotRegisterApplicationContext(this.context);
-		assertThat(this.context.getParent().getBean(ApplicationArguments.class).getNonOptionArgs())
-			.contains("foo.bar=baz");
+		ApplicationContext parent = this.context.getParent();
+		assertThat(parent).isNotNull();
+		assertThat(parent.getBean(ApplicationArguments.class).getNonOptionArgs()).contains("foo.bar=baz");
 		assertThat(this.context.getBean(ApplicationArguments.class).getNonOptionArgs()).contains("foo.bar=baz");
 	}
 
@@ -154,7 +159,9 @@ class SpringApplicationBuilderTests {
 		then(((SpyApplicationContext) this.context).getApplicationContext()).should()
 			.setParent(any(ApplicationContext.class));
 		assertThat(SpringApplicationShutdownHookInstance.get()).didNotRegisterApplicationContext(this.context);
-		assertThat(this.context.getParent().getBean(ApplicationArguments.class).getNonOptionArgs()).contains("a=alpha");
+		ApplicationContext parent = this.context.getParent();
+		assertThat(parent).isNotNull();
+		assertThat(parent.getBean(ApplicationArguments.class).getNonOptionArgs()).contains("a=alpha");
 		assertThat(this.context.getBean(ApplicationArguments.class).getNonOptionArgs()).contains("b=bravo");
 	}
 
@@ -188,7 +195,9 @@ class SpringApplicationBuilderTests {
 		application.resourceLoader(new DefaultResourceLoader(classLoader));
 		application.parent(ExampleConfig.class);
 		this.context = application.run();
-		assertThat(((SpyApplicationContext) this.context).getResourceLoader().getClassLoader()).isEqualTo(classLoader);
+		ResourceLoader resourceLoader = ((SpyApplicationContext) this.context).getResourceLoader();
+		assertThat(resourceLoader).isNotNull();
+		assertThat(resourceLoader.getClassLoader()).isEqualTo(classLoader);
 	}
 
 	@Test
@@ -212,8 +221,10 @@ class SpringApplicationBuilderTests {
 		this.context = application.run();
 		assertThat(this.context.getEnvironment().acceptsProfiles(Profiles.of("node"))).isTrue();
 		assertThat(this.context.getEnvironment().getProperty("transport")).isEqualTo("redis");
-		assertThat(this.context.getParent().getEnvironment().acceptsProfiles(Profiles.of("node"))).isTrue();
-		assertThat(this.context.getParent().getEnvironment().getProperty("transport")).isEqualTo("redis");
+		ApplicationContext parent = this.context.getParent();
+		assertThat(parent).isNotNull();
+		assertThat(parent.getEnvironment().acceptsProfiles(Profiles.of("node"))).isTrue();
+		assertThat(parent.getEnvironment().getProperty("transport")).isEqualTo("redis");
 		// only defined in node profile
 		assertThat(this.context.getEnvironment().getProperty("bar")).isEqualTo("spam");
 	}
@@ -227,7 +238,9 @@ class SpringApplicationBuilderTests {
 			.web(WebApplicationType.NONE);
 		this.context = application.run();
 		assertThat(this.context.getEnvironment().acceptsProfiles(Profiles.of("node", "admin"))).isTrue();
-		assertThat(this.context.getParent().getEnvironment().acceptsProfiles(Profiles.of("admin"))).isFalse();
+		ApplicationContext parent = this.context.getParent();
+		assertThat(parent).isNotNull();
+		assertThat(parent.getEnvironment().acceptsProfiles(Profiles.of("admin"))).isFalse();
 	}
 
 	@Test
@@ -240,8 +253,10 @@ class SpringApplicationBuilderTests {
 		shared.profiles("parent");
 		this.context = application.run();
 		assertThat(this.context.getEnvironment().acceptsProfiles(Profiles.of("node", "admin"))).isTrue();
-		assertThat(this.context.getParent().getEnvironment().acceptsProfiles(Profiles.of("node", "parent"))).isTrue();
-		assertThat(this.context.getParent().getEnvironment().acceptsProfiles(Profiles.of("admin"))).isFalse();
+		ApplicationContext parent = this.context.getParent();
+		assertThat(parent).isNotNull();
+		assertThat(parent.getEnvironment().acceptsProfiles(Profiles.of("node", "parent"))).isTrue();
+		assertThat(parent.getEnvironment().acceptsProfiles(Profiles.of("admin"))).isFalse();
 	}
 
 	@Test
@@ -257,7 +272,9 @@ class SpringApplicationBuilderTests {
 		assertThat(this.context.getEnvironment().acceptsProfiles(Profiles.of("node", "admin"))).isTrue();
 		// Now they share an Environment explicitly so there's no way to keep the profiles
 		// separate
-		assertThat(this.context.getParent().getEnvironment().acceptsProfiles(Profiles.of("admin"))).isTrue();
+		ApplicationContext parent = this.context.getParent();
+		assertThat(parent).isNotNull();
+		assertThat(parent.getEnvironment().acceptsProfiles(Profiles.of("admin"))).isTrue();
 	}
 
 	@Test
@@ -330,7 +347,8 @@ class SpringApplicationBuilderTests {
 		SpringApplicationBuilder applicationBuilder = new SpringApplicationBuilder(resourceLoader,
 				ExampleConfig.class) {
 			@Override
-			protected SpringApplication createSpringApplication(ResourceLoader resourceLoader, Class<?>... sources) {
+			protected SpringApplication createSpringApplication(@Nullable ResourceLoader resourceLoader,
+					Class<?>... sources) {
 				return new CustomSpringApplication(resourceLoader, sources);
 			}
 		};
@@ -351,9 +369,9 @@ class SpringApplicationBuilderTests {
 
 	static class CustomSpringApplication extends SpringApplication {
 
-		private final ResourceLoader resourceLoader;
+		private final @Nullable ResourceLoader resourceLoader;
 
-		CustomSpringApplication(ResourceLoader resourceLoader, Class<?>... primarySources) {
+		CustomSpringApplication(@Nullable ResourceLoader resourceLoader, Class<?>... primarySources) {
 			super(resourceLoader, primarySources);
 			this.resourceLoader = resourceLoader;
 		}
@@ -364,10 +382,10 @@ class SpringApplicationBuilderTests {
 
 		private final ConfigurableApplicationContext applicationContext = spy(new AnnotationConfigApplicationContext());
 
-		private ResourceLoader resourceLoader;
+		private @Nullable ResourceLoader resourceLoader;
 
 		@Override
-		public void setParent(ApplicationContext parent) {
+		public void setParent(@Nullable ApplicationContext parent) {
 			this.applicationContext.setParent(parent);
 		}
 
@@ -381,7 +399,7 @@ class SpringApplicationBuilderTests {
 			this.resourceLoader = resourceLoader;
 		}
 
-		ResourceLoader getResourceLoader() {
+		@Nullable ResourceLoader getResourceLoader() {
 			return this.resourceLoader;
 		}
 
@@ -392,7 +410,7 @@ class SpringApplicationBuilderTests {
 		}
 
 		@Override
-		public ApplicationContext getParent() {
+		public @Nullable ApplicationContext getParent() {
 			return this.applicationContext.getParent();
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/cloud/CloudPlatformTests.java

@@ -58,6 +58,7 @@ class CloudPlatformTests {
 	void getActiveWhenHasVcapApplicationShouldReturnCloudFoundry() {
 		Environment environment = new MockEnvironment().withProperty("VCAP_APPLICATION", "---");
 		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNotNull();
 		assertThat(platform).isEqualTo(CloudPlatform.CLOUD_FOUNDRY);
 		assertThat(platform.isActive(environment)).isTrue();
 	}
@@ -66,6 +67,7 @@ class CloudPlatformTests {
 	void getActiveWhenHasVcapServicesShouldReturnCloudFoundry() {
 		Environment environment = new MockEnvironment().withProperty("VCAP_SERVICES", "---");
 		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNotNull();
 		assertThat(platform).isEqualTo(CloudPlatform.CLOUD_FOUNDRY);
 		assertThat(platform.isActive(environment)).isTrue();
 	}
@@ -74,6 +76,7 @@ class CloudPlatformTests {
 	void getActiveWhenHasDynoShouldReturnHeroku() {
 		Environment environment = new MockEnvironment().withProperty("DYNO", "---");
 		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNotNull();
 		assertThat(platform).isEqualTo(CloudPlatform.HEROKU);
 		assertThat(platform.isActive(environment)).isTrue();
 	}
@@ -82,6 +85,7 @@ class CloudPlatformTests {
 	void getActiveWhenHasHcLandscapeShouldReturnSap() {
 		Environment environment = new MockEnvironment().withProperty("HC_LANDSCAPE", "---");
 		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNotNull();
 		assertThat(platform).isEqualTo(CloudPlatform.SAP);
 		assertThat(platform.isActive(environment)).isTrue();
 	}
@@ -90,6 +94,7 @@ class CloudPlatformTests {
 	void getActiveWhenHasNomadAllocIdShouldReturnNomad() {
 		Environment environment = new MockEnvironment().withProperty("NOMAD_ALLOC_ID", "---");
 		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNotNull();
 		assertThat(platform).isEqualTo(CloudPlatform.NOMAD);
 		assertThat(platform.isActive(environment)).isTrue();
 	}
@@ -101,6 +106,7 @@ class CloudPlatformTests {
 		envVars.put("KUBERNETES_SERVICE_PORT", "8080");
 		Environment environment = getEnvironmentWithEnvVariables(envVars);
 		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNotNull();
 		assertThat(platform).isEqualTo(CloudPlatform.KUBERNETES);
 		assertThat(platform.isActive(environment)).isTrue();
 	}
@@ -128,6 +134,7 @@ class CloudPlatformTests {
 		envVars.put("EXAMPLE_SERVICE_PORT", "8080");
 		Environment environment = getEnvironmentWithEnvVariables(envVars);
 		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNotNull();
 		assertThat(platform).isEqualTo(CloudPlatform.KUBERNETES);
 		assertThat(platform.isActive(environment)).isTrue();
 	}
@@ -149,6 +156,7 @@ class CloudPlatformTests {
 		envVars.put("WEBSITE_SKU", "1234");
 		Environment environment = getEnvironmentWithEnvVariables(envVars);
 		CloudPlatform platform = CloudPlatform.getActive(environment);
+		assertThat(platform).isNotNull();
 		assertThat(platform).isEqualTo(CloudPlatform.AZURE_APP_SERVICE);
 		assertThat(platform.isActive(environment)).isTrue();
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/ApplicationPidFileWriterTests.java

@@ -57,6 +57,7 @@ class ApplicationPidFileWriterTests {
 			new String[] {}, mock(ConfigurableApplicationContext.class));
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File tempDir;
 
 	@BeforeEach

core/spring-boot/src/test/java/org/springframework/boot/context/ContextIdApplicationContextInitializerTests.java

@@ -20,6 +20,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -87,7 +88,8 @@ class ContextIdApplicationContextInitializerTests {
 		assertThat(createContext(parent).getId()).isEqualTo("application");
 	}
 
-	private ConfigurableApplicationContext createContext(ConfigurableApplicationContext parent, String... properties) {
+	private ConfigurableApplicationContext createContext(@Nullable ConfigurableApplicationContext parent,
+			String... properties) {
 		ConfigurableApplicationContext context = new AnnotationConfigApplicationContext();
 		TestPropertySourceUtils.addInlinedPropertiesToEnvironment(context, properties);
 		if (parent != null) {

core/spring-boot/src/test/java/org/springframework/boot/context/TypeExcludeFilterTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -39,7 +40,7 @@ import static org.assertj.core.api.Assertions.assertThatExceptionOfType;
  */
 class TypeExcludeFilterTests {
 
-	private AnnotationConfigApplicationContext context;
+	private @Nullable AnnotationConfigApplicationContext context;
 
 	@AfterEach
 	void cleanUp() {
@@ -56,8 +57,10 @@ class TypeExcludeFilterTests {
 		this.context.register(Config.class);
 		this.context.refresh();
 		assertThat(this.context.getBean(ExampleComponent.class)).isNotNull();
-		assertThatExceptionOfType(NoSuchBeanDefinitionException.class)
-			.isThrownBy(() -> this.context.getBean(ExampleFilteredComponent.class));
+		assertThatExceptionOfType(NoSuchBeanDefinitionException.class).isThrownBy(() -> {
+			assertThat(this.context).isNotNull();
+			this.context.getBean(ExampleFilteredComponent.class);
+		});
 	}
 
 	@Configuration(proxyBeanMethods = false)

core/spring-boot/src/test/java/org/springframework/boot/context/annotation/ConfigurationsTests.java

@@ -27,6 +27,7 @@ import java.util.Set;
 import java.util.function.Function;
 import java.util.function.UnaryOperator;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.Ordered;
@@ -44,6 +45,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 class ConfigurationsTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenClassesIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new TestConfigurations((Collection<Class<?>>) null))
 			.withMessageContaining("'classes' must not be null");
@@ -91,7 +93,7 @@ class ConfigurationsTests {
 		}
 
 		TestConfigurations(UnaryOperator<Collection<Class<?>>> sorter, Collection<Class<?>> classes,
-				Function<Class<?>, String> beanNameGenerator) {
+				@Nullable Function<Class<?>, String> beanNameGenerator) {
 			super(sorter, classes, beanNameGenerator);
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentContributorPlaceholdersResolverTests.java

@@ -22,6 +22,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.origin.Origin;
@@ -120,7 +121,9 @@ class ConfigDataEnvironmentContributorPlaceholdersResolverTests {
 	private Consumer<InactiveConfigDataAccessException> propertyNameAndOriginOf(String propertyName, String origin) {
 		return (ex) -> {
 			assertThat(ex.getPropertyName()).isEqualTo(propertyName);
-			assertThat(((PropertySourceOrigin) (ex.getOrigin())).getPropertySource().getName()).isEqualTo(origin);
+			PropertySourceOrigin actualOrigin = (PropertySourceOrigin) (ex.getOrigin());
+			assertThat(actualOrigin).isNotNull();
+			assertThat(actualOrigin.getPropertySource().getName()).isEqualTo(origin);
 		};
 	}
 
@@ -135,7 +138,7 @@ class ConfigDataEnvironmentContributorPlaceholdersResolverTests {
 		}
 
 		@Override
-		public Origin getOrigin(String key) {
+		public @Nullable Origin getOrigin(String key) {
 			if (getSource().containsKey(key)) {
 				return new PropertySourceOrigin(this, key);
 			}
@@ -155,7 +158,7 @@ class ConfigDataEnvironmentContributorPlaceholdersResolverTests {
 		}
 
 		@Override
-		boolean isActive(ConfigDataActivationContext activationContext) {
+		boolean isActive(@Nullable ConfigDataActivationContext activationContext) {
 			return this.active;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentContributorTests.java

@@ -23,6 +23,7 @@ import java.util.Iterator;
 import java.util.List;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.cloud.CloudPlatform;
@@ -30,7 +31,9 @@ import org.springframework.boot.context.config.ConfigData.Option;
 import org.springframework.boot.context.config.ConfigData.PropertySourceOptions;
 import org.springframework.boot.context.config.ConfigDataEnvironmentContributor.ImportPhase;
 import org.springframework.boot.context.config.ConfigDataEnvironmentContributor.Kind;
+import org.springframework.boot.context.properties.source.ConfigurationProperty;
 import org.springframework.boot.context.properties.source.ConfigurationPropertyName;
+import org.springframework.boot.context.properties.source.ConfigurationPropertySource;
 import org.springframework.core.convert.ConversionService;
 import org.springframework.core.convert.support.DefaultConversionService;
 import org.springframework.mock.env.MockPropertySource;
@@ -110,9 +113,11 @@ class ConfigDataEnvironmentContributorTests {
 		ConfigData configData = new ConfigData(Collections.singleton(propertySource));
 		ConfigDataEnvironmentContributor contributor = ConfigDataEnvironmentContributor.ofUnboundImport(null, null,
 				false, configData, 0, this.conversionService, ConfigDataEnvironmentUpdateListener.NONE);
-		assertThat(contributor.getConfigurationPropertySource()
-			.getConfigurationProperty(ConfigurationPropertyName.of("spring"))
-			.getValue()).isEqualTo("boot");
+		ConfigurationPropertySource source = contributor.getConfigurationPropertySource();
+		assertThat(source).isNotNull();
+		ConfigurationProperty spring = source.getConfigurationProperty(ConfigurationPropertyName.of("spring"));
+		assertThat(spring).isNotNull();
+		assertThat(spring.getValue()).isEqualTo("boot");
 	}
 
 	@Test
@@ -379,8 +384,8 @@ class ConfigDataEnvironmentContributorTests {
 				new ConfigData(Collections.singleton(new MockPropertySource())), 0);
 	}
 
-	private ConfigDataEnvironmentContributor createBoundContributor(ConfigDataResource resource, ConfigData configData,
-			int propertySourceIndex) {
+	private ConfigDataEnvironmentContributor createBoundContributor(@Nullable ConfigDataResource resource,
+			ConfigData configData, int propertySourceIndex) {
 		ConfigDataEnvironmentContributor contributor = ConfigDataEnvironmentContributor.ofUnboundImport(TEST_LOCATION,
 				resource, false, configData, propertySourceIndex, this.conversionService,
 				ConfigDataEnvironmentUpdateListener.NONE);
@@ -394,7 +399,9 @@ class ConfigDataEnvironmentContributorTests {
 	}
 
 	private String getLocationName(ConfigDataEnvironmentContributor contributor) {
-		return contributor.getResource().toString();
+		ConfigDataResource resource = contributor.getResource();
+		assertThat(resource).isNotNull();
+		return resource.toString();
 	}
 
 	static class TestResource extends ConfigDataResource {

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentPostProcessorImportCombinedWithProfileSpecificIntegrationTests.java

@@ -63,6 +63,7 @@ class ConfigDataEnvironmentPostProcessorImportCombinedWithProfileSpecificIntegra
 	private SpringApplication application;
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	public File temp;
 
 	@BeforeEach

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentPostProcessorIntegrationTests.java

@@ -32,6 +32,7 @@ import java.util.Properties;
 import java.util.UUID;
 
 import org.assertj.core.api.Condition;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -84,6 +85,7 @@ class ConfigDataEnvironmentPostProcessorIntegrationTests {
 	private SpringApplication application;
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	public File temp;
 
 	@BeforeEach
@@ -814,7 +816,7 @@ class ConfigDataEnvironmentPostProcessorIntegrationTests {
 		MapPropertySource propertySource = new MapPropertySource("defaultProperties", source) {
 
 			@Override
-			public Object getProperty(String name) {
+			public @Nullable Object getProperty(String name) {
 				if ("spring.config.name".equals(name)) {
 					return "gh17001";
 				}
@@ -1088,8 +1090,11 @@ class ConfigDataEnvironmentPostProcessorIntegrationTests {
 		binder.bind("my.value", Bindable.of(String.class), bindHandler);
 		assertThat(properties).hasSize(1);
 		Origin origin = properties.get(0).getOrigin();
+		assertThat(origin).isNotNull();
 		assertThat(origin.toString()).contains("imported.properties");
-		assertThat(origin.getParent().toString()).contains("application.properties");
+		Origin parent = origin.getParent();
+		assertThat(parent).isNotNull();
+		assertThat(parent.toString()).contains("application.properties");
 	}
 
 	@Test
@@ -1315,7 +1320,7 @@ class ConfigDataEnvironmentPostProcessorIntegrationTests {
 	static class Loader implements ConfigDataLoader<TestConfigDataResource> {
 
 		@Override
-		public ConfigData load(ConfigDataLoaderContext context, TestConfigDataResource resource)
+		public @Nullable ConfigData load(ConfigDataLoaderContext context, TestConfigDataResource resource)
 				throws IOException, ConfigDataResourceNotFoundException {
 			if (resource.isOptional()) {
 				return null;

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentPostProcessorTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.context.config;
 import java.util.Collections;
 import java.util.function.Supplier;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.SpringApplication;
@@ -51,13 +52,15 @@ class ConfigDataEnvironmentPostProcessorTests {
 
 	private final SpringApplication application = new SpringApplication();
 
-	private ConfigDataEnvironment configDataEnvironment;
+	private @Nullable ConfigDataEnvironment configDataEnvironment;
 
-	private ConfigDataEnvironmentPostProcessor postProcessor;
+	private @Nullable ConfigDataEnvironmentPostProcessor postProcessor;
 
 	@Test
 	void postProcessEnvironmentWhenNoLoaderCreatesDefaultLoaderInstance() {
 		setupMocksAndSpies();
+		assertThat(this.configDataEnvironment).isNotNull();
+		assertThat(this.postProcessor).isNotNull();
 		willReturn(this.configDataEnvironment).given(this.postProcessor).getConfigDataEnvironment(any(), any(), any());
 		this.postProcessor.postProcessEnvironment(this.environment, this.application);
 		then(this.postProcessor).should()
@@ -70,6 +73,8 @@ class ConfigDataEnvironmentPostProcessorTests {
 	@Test
 	void postProcessEnvironmentWhenCustomLoaderUsesSpecifiedLoaderInstance() {
 		setupMocksAndSpies();
+		assertThat(this.configDataEnvironment).isNotNull();
+		assertThat(this.postProcessor).isNotNull();
 		ResourceLoader resourceLoader = mock(ResourceLoader.class);
 		this.application.setResourceLoader(resourceLoader);
 		willReturn(this.configDataEnvironment).given(this.postProcessor).getConfigDataEnvironment(any(), any(), any());
@@ -83,6 +88,8 @@ class ConfigDataEnvironmentPostProcessorTests {
 	@Test
 	void postProcessEnvironmentWhenHasAdditionalProfilesOnSpringApplicationUsesAdditionalProfiles() {
 		setupMocksAndSpies();
+		assertThat(this.configDataEnvironment).isNotNull();
+		assertThat(this.postProcessor).isNotNull();
 		this.application.setAdditionalProfiles("dev");
 		willReturn(this.configDataEnvironment).given(this.postProcessor).getConfigDataEnvironment(any(), any(), any());
 		this.postProcessor.postProcessEnvironment(this.environment, this.application);
@@ -95,6 +102,8 @@ class ConfigDataEnvironmentPostProcessorTests {
 	@Test
 	void postProcessEnvironmentWhenNoActiveProfiles() {
 		setupMocksAndSpies();
+		assertThat(this.configDataEnvironment).isNotNull();
+		assertThat(this.postProcessor).isNotNull();
 		willReturn(this.configDataEnvironment).given(this.postProcessor).getConfigDataEnvironment(any(), any(), any());
 		this.postProcessor.postProcessEnvironment(this.environment, this.application);
 		then(this.postProcessor).should().getConfigDataEnvironment(any(), any(ResourceLoader.class), any());
@@ -113,7 +122,9 @@ class ConfigDataEnvironmentPostProcessorTests {
 		assertThat(this.environment.getPropertySources()).hasSizeGreaterThan(before);
 		assertThat(this.environment.getActiveProfiles()).containsExactly("dev");
 		assertThat(listener.getAddedPropertySources()).isNotEmpty();
-		assertThat(listener.getProfiles().getActive()).containsExactly("dev");
+		Profiles profiles = listener.getProfiles();
+		assertThat(profiles).isNotNull();
+		assertThat(profiles.getActive()).containsExactly("dev");
 		assertThat(listener.getAddedPropertySources().stream().anyMatch((added) -> hasDevProfile(added.getResource())))
 			.isTrue();
 	}
@@ -147,7 +158,7 @@ class ConfigDataEnvironmentPostProcessorTests {
 		this.postProcessor = spy(new ConfigDataEnvironmentPostProcessor(Supplier::get, new DefaultBootstrapContext()));
 	}
 
-	private boolean hasDevProfile(ConfigDataResource resource) {
+	private boolean hasDevProfile(@Nullable ConfigDataResource resource) {
 		return (resource instanceof StandardConfigDataResource standardResource)
 				&& "dev".equals(standardResource.getProfile());
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataEnvironmentTests.java

@@ -27,6 +27,7 @@ import java.util.Map;
 import java.util.function.Supplier;
 
 import org.assertj.core.api.InstanceOfAssertFactories;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.TestInfo;
 import org.junit.jupiter.params.ParameterizedTest;
@@ -81,8 +82,9 @@ class ConfigDataEnvironmentTests {
 		this.environment.setProperty("spring", "boot");
 		TestConfigDataEnvironment configDataEnvironment = new TestConfigDataEnvironment(this.logFactory,
 				this.bootstrapContext, this.environment, this.resourceLoader, this.additionalProfiles, null);
-		assertThat(configDataEnvironment.getConfigDataLocationResolversBinder().bind("spring", String.class).get())
-			.isEqualTo("boot");
+		Binder binder = configDataEnvironment.getConfigDataLocationResolversBinder();
+		assertThat(binder).isNotNull();
+		assertThat(binder.bind("spring", String.class).get()).isEqualTo("boot");
 	}
 
 	@Test
@@ -335,8 +337,9 @@ class ConfigDataEnvironmentTests {
 		AddedPropertySource addedPropertySource = listener.getAddedPropertySources().get(0);
 		assertThat(addedPropertySource.getPropertySource().getProperty("spring")).isEqualTo("boot");
 		assertThat(addedPropertySource.getLocation()).hasToString("classpath:custom/config.properties");
-		assertThat(addedPropertySource.getResource().toString()).contains("class path resource")
-			.contains("custom/config.properties");
+		ConfigDataResource resource = addedPropertySource.getResource();
+		assertThat(resource).isNotNull();
+		assertThat(resource.toString()).contains("class path resource").contains("custom/config.properties");
 	}
 
 	@Test
@@ -346,7 +349,9 @@ class ConfigDataEnvironmentTests {
 		ConfigDataEnvironment configDataEnvironment = new ConfigDataEnvironment(this.logFactory, this.bootstrapContext,
 				this.environment, this.resourceLoader, this.additionalProfiles, listener);
 		configDataEnvironment.processAndApply();
-		assertThat(listener.getProfiles().getActive()).containsExactly("one", "two", "three");
+		Profiles profiles = listener.getProfiles();
+		assertThat(profiles).isNotNull();
+		assertThat(profiles.getActive()).containsExactly("one", "two", "three");
 	}
 
 	@Test
@@ -384,11 +389,12 @@ class ConfigDataEnvironmentTests {
 
 	static class TestConfigDataEnvironment extends ConfigDataEnvironment {
 
-		private Binder configDataLocationResolversBinder;
+		private @Nullable Binder configDataLocationResolversBinder;
 
 		TestConfigDataEnvironment(DeferredLogFactory logFactory, ConfigurableBootstrapContext bootstrapContext,
 				ConfigurableEnvironment environment, ResourceLoader resourceLoader,
-				Collection<String> additionalProfiles, ConfigDataEnvironmentUpdateListener environmentUpdateListener) {
+				Collection<String> additionalProfiles,
+				@Nullable ConfigDataEnvironmentUpdateListener environmentUpdateListener) {
 			super(logFactory, bootstrapContext, environment, resourceLoader, additionalProfiles,
 					environmentUpdateListener);
 		}
@@ -400,7 +406,7 @@ class ConfigDataEnvironmentTests {
 			return super.createConfigDataLocationResolvers(logFactory, bootstrapContext, binder, resourceLoader);
 		}
 
-		Binder getConfigDataLocationResolversBinder() {
+		@Nullable Binder getConfigDataLocationResolversBinder() {
 			return this.configDataLocationResolversBinder;
 		}
 
@@ -409,7 +415,7 @@ class ConfigDataEnvironmentTests {
 	static class SeparateClassLoaderConfigDataLoader implements ConfigDataLoader<ConfigDataResource> {
 
 		@Override
-		public ConfigData load(ConfigDataLoaderContext context, ConfigDataResource resource)
+		public @Nullable ConfigData load(ConfigDataLoaderContext context, ConfigDataResource resource)
 				throws IOException, ConfigDataResourceNotFoundException {
 			return null;
 		}

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataImporterTests.java

@@ -47,24 +47,31 @@ class ConfigDataImporterTests {
 	private final DeferredLogFactory logFactory = Supplier::get;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ConfigDataLocationResolvers resolvers;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ConfigDataLoaders loaders;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Binder binder;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ConfigDataLocationResolverContext locationResolverContext;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ConfigDataLoaderContext loaderContext;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ConfigDataActivationContext activationContext;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Profiles profiles;
 
 	@BeforeEach

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataLoaderTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.context.config;
 
 import java.io.IOException;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -43,7 +44,8 @@ class ConfigDataLoaderTests {
 	static class TestConfigDataLoader implements ConfigDataLoader<TestConfigDataResource> {
 
 		@Override
-		public ConfigData load(ConfigDataLoaderContext context, TestConfigDataResource resource) throws IOException {
+		public @Nullable ConfigData load(ConfigDataLoaderContext context, TestConfigDataResource resource)
+				throws IOException {
 			return null;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataLoadersTests.java

@@ -16,7 +16,6 @@
 
 package org.springframework.boot.context.config;
 
-import java.io.File;
 import java.io.IOException;
 import java.util.Arrays;
 import java.util.List;
@@ -25,7 +24,6 @@ import java.util.function.Supplier;
 import org.apache.commons.logging.Log;
 import org.assertj.core.api.InstanceOfAssertFactories;
 import org.junit.jupiter.api.Test;
-import org.junit.jupiter.api.io.TempDir;
 
 import org.springframework.boot.bootstrap.BootstrapContext;
 import org.springframework.boot.bootstrap.BootstrapRegistry;
@@ -56,9 +54,6 @@ class ConfigDataLoadersTests {
 
 	private final ConfigDataLoaderContext context = mock(ConfigDataLoaderContext.class);
 
-	@TempDir
-	private File tempDir;
-
 	@Test
 	void createWhenLoaderHasDeferredLogFactoryParameterInjectsDeferredLogFactory() {
 		MockSpringFactoriesLoader springFactoriesLoader = new MockSpringFactoriesLoader();
@@ -103,6 +98,7 @@ class ConfigDataLoadersTests {
 				springFactoriesLoader);
 		TestConfigDataResource location = new TestConfigDataResource("test");
 		ConfigData loaded = loaders.load(this.context, location);
+		assertThat(loaded).isNotNull();
 		assertThat(getLoader(loaded)).isInstanceOf(TestConfigDataLoader.class);
 	}
 
@@ -136,11 +132,14 @@ class ConfigDataLoadersTests {
 				springFactoriesLoader);
 		TestConfigDataResource location = new TestConfigDataResource("test");
 		ConfigData loaded = loaders.load(this.context, location);
+		assertThat(loaded).isNotNull();
 		assertThat(getLoader(loaded)).isInstanceOf(SpecificConfigDataLoader.class);
 	}
 
 	private ConfigDataLoader<?> getLoader(ConfigData loaded) {
-		return (ConfigDataLoader<?>) loaded.getPropertySources().get(0).getProperty("loader");
+		ConfigDataLoader<?> result = (ConfigDataLoader<?>) loaded.getPropertySources().get(0).getProperty("loader");
+		assertThat(result).isNotNull();
+		return result;
 	}
 
 	private static ConfigData createConfigData(ConfigDataLoader<?> loader, ConfigDataResource resource) {

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataLocationNotFoundExceptionTests.java

@@ -39,6 +39,7 @@ class ConfigDataLocationNotFoundExceptionTests {
 			this.location);
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenLocationIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigDataLocationNotFoundException(null))
 			.withMessage("'location' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataLocationResolverTests.java

@@ -16,10 +16,14 @@
 
 package org.springframework.boot.context.config;
 
+import java.util.Collections;
 import java.util.List;
 
 import org.junit.jupiter.api.Test;
 
+import org.springframework.boot.context.properties.bind.Binder;
+import org.springframework.mock.env.MockEnvironment;
+
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
 
@@ -37,7 +41,10 @@ class ConfigDataLocationResolverTests {
 
 	@Test
 	void resolveProfileSpecificReturnsEmptyList() {
-		assertThat(this.resolver.resolveProfileSpecific(this.context, null, null)).isEmpty();
+		ConfigDataLocation location = ConfigDataLocation.of("location");
+		MockEnvironment environment = new MockEnvironment();
+		Profiles profiles = new Profiles(environment, Binder.get(environment), null);
+		assertThat(this.resolver.resolveProfileSpecific(this.context, location, profiles)).isEmpty();
 	}
 
 	static class TestConfigDataLocationResolver implements ConfigDataLocationResolver<ConfigDataResource> {
@@ -50,7 +57,7 @@ class ConfigDataLocationResolverTests {
 		@Override
 		public List<ConfigDataResource> resolve(ConfigDataLocationResolverContext context,
 				ConfigDataLocation location) {
-			return null;
+			return Collections.emptyList();
 		}
 
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataLocationResolversTests.java

@@ -56,15 +56,19 @@ class ConfigDataLocationResolversTests {
 	private final DefaultBootstrapContext bootstrapContext = new DefaultBootstrapContext();
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Binder binder;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ConfigDataLocationResolverContext context;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Profiles profiles;
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	private File tempDir;
 
 	@Test

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataLocationRuntimeHintsTests.java

@@ -20,6 +20,7 @@ import java.util.List;
 import java.util.UUID;
 import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.aot.hint.ResourcePatternHint;
@@ -60,7 +61,7 @@ class ConfigDataLocationRuntimeHintsTests {
 		RuntimeHints hints = new RuntimeHints();
 		new TestConfigDataLocationRuntimeHints() {
 			@Override
-			protected List<String> getFileNames(ClassLoader classLoader) {
+			protected List<String> getFileNames(@Nullable ClassLoader classLoader) {
 				return List.of("test");
 			}
 
@@ -77,7 +78,7 @@ class ConfigDataLocationRuntimeHintsTests {
 		RuntimeHints hints = new RuntimeHints();
 		new TestConfigDataLocationRuntimeHints() {
 			@Override
-			protected List<String> getLocations(ClassLoader classLoader) {
+			protected List<String> getLocations(@Nullable ClassLoader classLoader) {
 				return List.of("config/");
 			}
 		}.registerHints(hints, Thread.currentThread().getContextClassLoader());
@@ -93,7 +94,7 @@ class ConfigDataLocationRuntimeHintsTests {
 		RuntimeHints hints = new RuntimeHints();
 		new ConfigDataLocationRuntimeHints() {
 			@Override
-			protected List<String> getExtensions(ClassLoader classLoader) {
+			protected List<String> getExtensions(@Nullable ClassLoader classLoader) {
 				return List.of(".conf");
 			}
 		}.registerHints(hints, Thread.currentThread().getContextClassLoader());
@@ -106,7 +107,7 @@ class ConfigDataLocationRuntimeHintsTests {
 		RuntimeHints hints = new RuntimeHints();
 		new ConfigDataLocationRuntimeHints() {
 			@Override
-			protected List<String> getLocations(ClassLoader classLoader) {
+			protected List<String> getLocations(@Nullable ClassLoader classLoader) {
 				return List.of(UUID.randomUUID().toString());
 			}
 		}.registerHints(hints, Thread.currentThread().getContextClassLoader());
@@ -138,7 +139,7 @@ class ConfigDataLocationRuntimeHintsTests {
 		}
 
 		@Override
-		protected SpringFactoriesLoader getSpringFactoriesLoader(ClassLoader classLoader) {
+		protected SpringFactoriesLoader getSpringFactoriesLoader(@Nullable ClassLoader classLoader) {
 			return this.springFactoriesLoader;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataNotFoundFailureAnalyzerTests.java

@@ -38,6 +38,7 @@ class ConfigDataNotFoundFailureAnalyzerTests {
 		ConfigDataLocation location = ConfigDataLocation.of("test");
 		ConfigDataLocationNotFoundException exception = new ConfigDataLocationNotFoundException(location);
 		FailureAnalysis result = this.analyzer.analyze(exception);
+		assertThat(result).isNotNull();
 		assertThat(result.getDescription()).isEqualTo("Config data location 'test' does not exist");
 		assertThat(result.getAction())
 			.isEqualTo("Check that the value 'test' is correct, or prefix it with 'optional:'");
@@ -48,6 +49,7 @@ class ConfigDataNotFoundFailureAnalyzerTests {
 		ConfigDataLocation location = ConfigDataLocation.of("optional:test");
 		ConfigDataLocationNotFoundException exception = new ConfigDataLocationNotFoundException(location);
 		FailureAnalysis result = this.analyzer.analyze(exception);
+		assertThat(result).isNotNull();
 		assertThat(result.getDescription()).isEqualTo("Config data location 'optional:test' does not exist");
 		assertThat(result.getAction()).isEqualTo("Check that the value 'optional:test' is correct");
 	}
@@ -57,6 +59,7 @@ class ConfigDataNotFoundFailureAnalyzerTests {
 		ConfigDataLocation location = ConfigDataLocation.of("test").withOrigin(new TestOrigin("origin"));
 		ConfigDataLocationNotFoundException exception = new ConfigDataLocationNotFoundException(location);
 		FailureAnalysis result = this.analyzer.analyze(exception);
+		assertThat(result).isNotNull();
 		assertThat(result.getDescription()).isEqualTo("Config data location 'test' does not exist");
 		assertThat(result.getAction())
 			.isEqualTo("Check that the value 'test' at origin is correct, or prefix it with 'optional:'");
@@ -67,6 +70,7 @@ class ConfigDataNotFoundFailureAnalyzerTests {
 		ConfigDataResource resource = new TestConfigDataResource("myresource");
 		ConfigDataResourceNotFoundException exception = new ConfigDataResourceNotFoundException(resource);
 		FailureAnalysis result = this.analyzer.analyze(exception);
+		assertThat(result).isNotNull();
 		assertThat(result.getDescription()).isEqualTo("Config data resource 'myresource' does not exist");
 		assertThat(result.getAction()).isEqualTo("Check that the value is correct");
 	}
@@ -78,6 +82,7 @@ class ConfigDataNotFoundFailureAnalyzerTests {
 		ConfigDataResourceNotFoundException exception = new ConfigDataResourceNotFoundException(resource)
 			.withLocation(location);
 		FailureAnalysis result = this.analyzer.analyze(exception);
+		assertThat(result).isNotNull();
 		assertThat(result.getDescription())
 			.isEqualTo("Config data resource 'myresource' via location 'test' does not exist");
 		assertThat(result.getAction())

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataPropertiesTests.java

@@ -20,6 +20,7 @@ import java.util.Arrays;
 import java.util.Collections;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.cloud.CloudPlatform;
@@ -39,9 +40,9 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class ConfigDataPropertiesTests {
 
-	private static final CloudPlatform NULL_CLOUD_PLATFORM = null;
+	private static final @Nullable CloudPlatform NULL_CLOUD_PLATFORM = null;
 
-	private static final Profiles NULL_PROFILES = null;
+	private static final @Nullable Profiles NULL_PROFILES = null;
 
 	private static final List<ConfigDataLocation> NO_IMPORTS = Collections.emptyList();
 
@@ -173,6 +174,7 @@ class ConfigDataPropertiesTests {
 		ConfigDataProperties properties = ConfigDataProperties.get(binder);
 		ConfigDataActivationContext context = new ConfigDataActivationContext(CloudPlatform.KUBERNETES,
 				createTestProfiles());
+		assertThat(properties).isNotNull();
 		assertThat(properties.isActive(context)).isTrue();
 	}
 
@@ -185,6 +187,7 @@ class ConfigDataPropertiesTests {
 		ConfigDataProperties properties = ConfigDataProperties.get(binder);
 		ConfigDataActivationContext context = new ConfigDataActivationContext(CloudPlatform.KUBERNETES,
 				createTestProfiles());
+		assertThat(properties).isNotNull();
 		assertThat(properties.isActive(context)).isFalse();
 	}
 
@@ -197,6 +200,7 @@ class ConfigDataPropertiesTests {
 		ConfigDataProperties properties = ConfigDataProperties.get(binder);
 		ConfigDataActivationContext context = new ConfigDataActivationContext(CloudPlatform.KUBERNETES,
 				createTestProfiles());
+		assertThat(properties).isNotNull();
 		assertThat(properties.isActive(context)).isFalse();
 	}
 
@@ -208,6 +212,7 @@ class ConfigDataPropertiesTests {
 		ConfigDataProperties properties = ConfigDataProperties.get(binder);
 		ConfigDataActivationContext context = new ConfigDataActivationContext(NULL_CLOUD_PLATFORM,
 				createTestProfiles());
+		assertThat(properties).isNotNull();
 		assertThat(properties.isActive(context)).isTrue();
 	}
 
@@ -217,6 +222,7 @@ class ConfigDataPropertiesTests {
 		source.put("spring.config.import", "one,two,three");
 		Binder binder = new Binder(source);
 		ConfigDataProperties properties = ConfigDataProperties.get(binder);
+		assertThat(properties).isNotNull();
 		assertThat(properties.getImports().get(1).getOrigin())
 			.hasToString("\"spring.config.import\" from property source \"source\"");
 	}
@@ -229,6 +235,7 @@ class ConfigDataPropertiesTests {
 		source.put("spring.config.import[2]", "three");
 		Binder binder = new Binder(source);
 		ConfigDataProperties properties = ConfigDataProperties.get(binder);
+		assertThat(properties).isNotNull();
 		assertThat(properties.getImports().get(1).getOrigin())
 			.hasToString("\"spring.config.import[1]\" from property source \"source\"");
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataResourceNotFoundExceptionTests.java

@@ -49,6 +49,7 @@ class ConfigDataResourceNotFoundExceptionTests {
 	private File missing;
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File temp;
 
 	@BeforeEach
@@ -61,6 +62,7 @@ class ConfigDataResourceNotFoundExceptionTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenResourceIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigDataResourceNotFoundException(null))
 			.withMessage("'resource' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigDataTests.java

@@ -42,12 +42,14 @@ import static org.mockito.Mockito.mock;
 class ConfigDataTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenPropertySourcesIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigData(null))
 			.withMessage("'propertySources' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenOptionsIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigData(Collections.emptyList(), (Option[]) null))
 			.withMessage("'options' must not be null");
@@ -127,8 +129,9 @@ class ConfigDataTests {
 	@Test
 	void propertySourceOptionsAlwaysReturnsSameOptionsEachTime() {
 		PropertySourceOptions options = PropertySourceOptions.always(Option.IGNORE_IMPORTS, Option.IGNORE_PROFILES);
-		assertThat(options.get(mock(PropertySource.class)).asSet()).containsExactly(Option.IGNORE_IMPORTS,
-				Option.IGNORE_PROFILES);
+		Options propertySourceOptions = options.get(mock(PropertySource.class));
+		assertThat(propertySourceOptions).isNotNull();
+		assertThat(propertySourceOptions.asSet()).containsExactly(Option.IGNORE_IMPORTS, Option.IGNORE_PROFILES);
 	}
 
 }

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigTreeConfigDataLoaderTests.java

@@ -44,6 +44,7 @@ class ConfigTreeConfigDataLoaderTests {
 	private final ConfigDataLoaderContext loaderContext = mock(ConfigDataLoaderContext.class);
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	Path directory;
 
 	@Test

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigTreeConfigDataLocationResolverTests.java

@@ -42,6 +42,7 @@ class ConfigTreeConfigDataLocationResolverTests {
 	private final ConfigDataLocationResolverContext context = mock(ConfigDataLocationResolverContext.class);
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File temp;
 
 	@Test

core/spring-boot/src/test/java/org/springframework/boot/context/config/ConfigTreeConfigDataResourceTests.java

@@ -33,12 +33,14 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 class ConfigTreeConfigDataResourceTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void constructorWhenPathStringIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigTreeConfigDataResource((String) null))
 			.withMessage("'path' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void constructorWhenPathIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigTreeConfigDataResource((Path) null))
 			.withMessage("'path' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/context/config/LocationResourceLoaderTests.java

@@ -40,6 +40,7 @@ class LocationResourceLoaderTests {
 	private final LocationResourceLoader loader = new LocationResourceLoader(new DefaultResourceLoader());
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	File temp;
 
 	@Test

core/spring-boot/src/test/java/org/springframework/boot/context/config/StandardConfigDataLocationResolverTests.java

@@ -258,7 +258,7 @@ class StandardConfigDataLocationResolverTests {
 		assertThat(locations).hasSize(1);
 		StandardConfigDataResource resolved = locations.get(0);
 		assertThat(resolved.getResource().getFilename()).endsWith("application-props-no-extension");
-		ConfigData loaded = new StandardConfigDataLoader().load(null, resolved);
+		ConfigData loaded = new StandardConfigDataLoader().load(mock(ConfigDataLoaderContext.class), resolved);
 		PropertySource<?> propertySource = loaded.getPropertySources().get(0);
 		assertThat(propertySource.getProperty("withnoextension")).isEqualTo("test");
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/config/StandardConfigDataResourceTests.java

@@ -46,12 +46,14 @@ class StandardConfigDataResourceTests {
 	private final Resource resource = mock(Resource.class);
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenReferenceIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new StandardConfigDataResource(null, this.resource))
 			.withMessage("'reference' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenResourceIsNullThrowsException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new StandardConfigDataResource(this.reference, null))
 			.withMessage("'resource' must not be null");
@@ -78,6 +80,7 @@ class StandardConfigDataResourceTests {
 	@WithResource(name = "test.resource", content = "test")
 	void equalsAndHashCodeWhenSameUnderlyingResource(@ResourcePath("test.resource") Path path) throws IOException {
 		Path directory = path.getParent();
+		assertThat(directory).isNotNull();
 		URLClassLoader classLoader = new URLClassLoader(new URL[] { directory.toUri().toURL() },
 				getClass().getClassLoader());
 		ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();

core/spring-boot/src/test/java/org/springframework/boot/context/config/TestConfigDataBootstrap.java

@@ -21,12 +21,16 @@ import java.util.Collections;
 import java.util.List;
 import java.util.function.Supplier;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.bootstrap.BootstrapContextClosedEvent;
 import org.springframework.boot.bootstrap.BootstrapRegistry.InstanceSupplier;
 import org.springframework.boot.context.properties.bind.Binder;
 import org.springframework.context.ApplicationListener;
 import org.springframework.core.env.MapPropertySource;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 /**
  * Test classes used with
  * {@link ConfigDataEnvironmentPostProcessorBootstrapContextIntegrationTests} to show how
@@ -50,6 +54,7 @@ class TestConfigDataBootstrap {
 			context.getBootstrapContext()
 				.registerIfAbsent(ResolverHelper.class, InstanceSupplier.from(() -> new ResolverHelper(location)));
 			ResolverHelper helper = context.getBootstrapContext().get(ResolverHelper.class);
+			assertThat(helper).isNotNull();
 			return Collections.singletonList(new Resource(helper));
 		}
 
@@ -63,6 +68,7 @@ class TestConfigDataBootstrap {
 				.registerIfAbsent(LoaderHelper.class,
 						(bootstrapContext) -> new LoaderHelper(location, () -> bootstrapContext.get(Binder.class)));
 			LoaderHelper helper = context.getBootstrapContext().get(LoaderHelper.class);
+			assertThat(helper).isNotNull();
 			context.getBootstrapContext().addCloseListener(helper);
 			return new ConfigData(
 					Collections.singleton(new MapPropertySource("loaded", Collections.singletonMap("test", "test"))));
@@ -118,11 +124,11 @@ class TestConfigDataBootstrap {
 			return this.location;
 		}
 
-		String getBound() {
+		@Nullable String getBound() {
 			return this.binder.get().bind("myprop", String.class).orElse(null);
 		}
 
-		String getProfileBound() {
+		@Nullable String getProfileBound() {
 			return this.binder.get().bind("myprofileprop", String.class).orElse(null);
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/config/TestConfigDataEnvironmentUpdateListener.java

@@ -20,17 +20,19 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.core.env.PropertySource;
 
 class TestConfigDataEnvironmentUpdateListener implements ConfigDataEnvironmentUpdateListener {
 
 	private final List<AddedPropertySource> addedPropertySources = new ArrayList<>();
 
-	private Profiles profiles;
+	private @Nullable Profiles profiles;
 
 	@Override
-	public void onPropertySourceAdded(PropertySource<?> propertySource, ConfigDataLocation location,
-			ConfigDataResource resource) {
+	public void onPropertySourceAdded(PropertySource<?> propertySource, @Nullable ConfigDataLocation location,
+			@Nullable ConfigDataResource resource) {
 		this.addedPropertySources.add(new AddedPropertySource(propertySource, location, resource));
 	}
 
@@ -43,7 +45,7 @@ class TestConfigDataEnvironmentUpdateListener implements ConfigDataEnvironmentUp
 		return Collections.unmodifiableList(this.addedPropertySources);
 	}
 
-	Profiles getProfiles() {
+	@Nullable Profiles getProfiles() {
 		return this.profiles;
 	}
 
@@ -51,12 +53,12 @@ class TestConfigDataEnvironmentUpdateListener implements ConfigDataEnvironmentUp
 
 		private final PropertySource<?> propertySource;
 
-		private final ConfigDataLocation location;
+		private final @Nullable ConfigDataLocation location;
 
-		private final ConfigDataResource resource;
+		private final @Nullable ConfigDataResource resource;
 
-		AddedPropertySource(PropertySource<?> propertySource, ConfigDataLocation location,
-				ConfigDataResource resource) {
+		AddedPropertySource(PropertySource<?> propertySource, @Nullable ConfigDataLocation location,
+				@Nullable ConfigDataResource resource) {
 			this.propertySource = propertySource;
 			this.location = location;
 			this.resource = resource;
@@ -66,11 +68,11 @@ class TestConfigDataEnvironmentUpdateListener implements ConfigDataEnvironmentUp
 			return this.propertySource;
 		}
 
-		ConfigDataLocation getLocation() {
+		@Nullable ConfigDataLocation getLocation() {
 			return this.location;
 		}
 
-		ConfigDataResource getResource() {
+		@Nullable ConfigDataResource getResource() {
 			return this.resource;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/event/EventPublishingRunListenerTests.java

@@ -32,6 +32,7 @@ import org.springframework.context.ApplicationListener;
 import org.springframework.context.support.StaticApplicationContext;
 import org.springframework.core.env.ConfigurableEnvironment;
 import org.springframework.core.env.StandardEnvironment;
+import org.springframework.mock.env.MockEnvironment;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.BDDMockito.given;
@@ -45,6 +46,8 @@ import static org.mockito.Mockito.mock;
  */
 class EventPublishingRunListenerTests {
 
+	private static final String[] NO_ARGS = new String[0];
+
 	@Test
 	void shouldPublishLifecycleEvents() {
 		DefaultBootstrapContext bootstrapContext = new DefaultBootstrapContext();
@@ -52,11 +55,11 @@ class EventPublishingRunListenerTests {
 		TestApplicationListener applicationListener = new TestApplicationListener();
 		SpringApplication application = mock(SpringApplication.class);
 		given(application.getListeners()).willReturn(Collections.singleton(applicationListener));
-		EventPublishingRunListener publishingListener = new EventPublishingRunListener(application, null);
+		EventPublishingRunListener publishingListener = new EventPublishingRunListener(application, NO_ARGS);
 		applicationListener.assertReceivedNoEvents();
 		publishingListener.starting(bootstrapContext);
 		applicationListener.assertReceivedEvent(ApplicationStartingEvent.class);
-		publishingListener.environmentPrepared(bootstrapContext, null);
+		publishingListener.environmentPrepared(bootstrapContext, new MockEnvironment());
 		applicationListener.assertReceivedEvent(ApplicationEnvironmentPreparedEvent.class);
 		publishingListener.contextPrepared(context);
 		applicationListener.assertReceivedEvent(ApplicationContextInitializedEvent.class);
@@ -78,7 +81,7 @@ class EventPublishingRunListenerTests {
 		ApplicationListener<ApplicationStartingEvent> listener = (event) -> event.getSpringApplication()
 			.addListeners(lateAddedApplicationListener);
 		application.addListeners(listener);
-		EventPublishingRunListener runListener = new EventPublishingRunListener(application, null);
+		EventPublishingRunListener runListener = new EventPublishingRunListener(application, NO_ARGS);
 		runListener.starting(bootstrapContext);
 		runListener.environmentPrepared(bootstrapContext, environment);
 		lateAddedApplicationListener.assertReceivedEvent(ApplicationEnvironmentPreparedEvent.class);

core/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerIntegrationTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.context.logging;
 
 import java.io.File;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.junit.jupiter.api.io.TempDir;
@@ -103,7 +104,7 @@ class LoggingApplicationListenerIntegrationTests {
 
 		private final LoggingSystem loggingSystem;
 
-		private final LogFile logFile;
+		private final @Nullable LogFile logFile;
 
 		SampleService(LoggingSystem loggingSystem, ObjectProvider<LogFile> logFile) {
 			this.loggingSystem = loggingSystem;

core/spring-boot/src/test/java/org/springframework/boot/context/logging/LoggingApplicationListenerTests.java

@@ -40,6 +40,7 @@ import ch.qos.logback.classic.Level;
 import ch.qos.logback.classic.LoggerContext;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -59,6 +60,7 @@ import org.springframework.boot.logging.AbstractLoggingSystem;
 import org.springframework.boot.logging.LogFile;
 import org.springframework.boot.logging.LogLevel;
 import org.springframework.boot.logging.LoggerConfiguration;
+import org.springframework.boot.logging.LoggerGroup;
 import org.springframework.boot.logging.LoggerGroups;
 import org.springframework.boot.logging.LoggingInitializationContext;
 import org.springframework.boot.logging.LoggingSystem;
@@ -118,6 +120,7 @@ class LoggingApplicationListenerTests {
 	private final GenericApplicationContext context = new GenericApplicationContext();
 
 	@TempDir
+	@SuppressWarnings("NullAway.Init")
 	public Path tempDir;
 
 	private File logFile;
@@ -149,14 +152,12 @@ class LoggingApplicationListenerTests {
 		System.clearProperty(LoggingSystem.class.getName());
 		System.clearProperty(LoggingSystem.SYSTEM_PROPERTY);
 		System.getProperties().keySet().retainAll(this.systemPropertyNames);
-		if (this.context != null) {
-			this.context.close();
-		}
+		this.context.close();
 	}
 
 	@Test
 	void baseConfigLocation() {
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.info("Hello world", new RuntimeException("Expected"));
 		assertThat(this.output).contains("Hello world");
 		assertThat(this.output).doesNotContain("???");
@@ -168,7 +169,7 @@ class LoggingApplicationListenerTests {
 	@WithNonDefaultXmlResource
 	void overrideConfigLocation() {
 		addPropertiesToEnvironment(this.context, "logging.config=classpath:nondefault.xml");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.info("Hello world");
 		assertThat(this.output).contains("Hello world").doesNotContain("???").startsWith("null ").endsWith("BOOTBOOT");
 	}
@@ -179,7 +180,7 @@ class LoggingApplicationListenerTests {
 		multicastEvent(this.listener,
 				new ApplicationStartingEvent(this.bootstrapContext, new SpringApplication(), NO_ARGS));
 		assertThatIllegalStateException()
-			.isThrownBy(() -> this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader()));
+			.isThrownBy(() -> this.listener.initialize(this.context.getEnvironment(), getClassLoader()));
 		assertThat(output).contains("Deliberately broken");
 	}
 
@@ -187,7 +188,7 @@ class LoggingApplicationListenerTests {
 	@WithNonDefaultXmlResource
 	void trailingWhitespaceInLoggingConfigShouldBeTrimmed() {
 		addPropertiesToEnvironment(this.context, "logging.config=classpath:nondefault.xml ");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.info("Hello world");
 		assertThat(this.output).contains("Hello world").doesNotContain("???").startsWith("null ").endsWith("BOOTBOOT");
 	}
@@ -196,7 +197,7 @@ class LoggingApplicationListenerTests {
 	void overrideConfigDoesNotExist() {
 		addPropertiesToEnvironment(this.context, "logging.config=doesnotexist.xml");
 		assertThatIllegalStateException()
-			.isThrownBy(() -> this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader()));
+			.isThrownBy(() -> this.listener.initialize(this.context.getEnvironment(), getClassLoader()));
 		assertThat(this.output)
 			.contains("Logging system failed to initialize using configuration from 'doesnotexist.xml'")
 			.doesNotContain("JoranException");
@@ -206,7 +207,7 @@ class LoggingApplicationListenerTests {
 	void azureDefaultLoggingConfigDoesNotCauseAFailure() {
 		addPropertiesToEnvironment(this.context,
 				"logging.config=-Djava.util.logging.config.file=\"d:\\home\\site\\wwwroot\\bin\\apache-tomcat-7.0.52\\conf\\logging.properties\"");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.info("Hello world");
 		assertThat(this.output).contains("Hello world").doesNotContain("???");
 		assertThat(new File(this.tempDir.toFile(), "/spring.log")).doesNotExist();
@@ -215,7 +216,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void tomcatNopLoggingConfigDoesNotCauseAFailure() {
 		addPropertiesToEnvironment(this.context, "LOGGING_CONFIG=-Dnop");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.info("Hello world");
 		assertThat(this.output).contains("Hello world").doesNotContain("???");
 		assertThat(new File(this.tempDir.toFile(), "/spring.log")).doesNotExist();
@@ -225,7 +226,7 @@ class LoggingApplicationListenerTests {
 	void overrideConfigBroken() {
 		addPropertiesToEnvironment(this.context, "logging.config=classpath:logback-broken.xml");
 		assertThatIllegalStateException().isThrownBy(() -> {
-			this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+			this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 			assertThat(this.output).contains(
 					"Logging system failed to initialize using configuration from 'classpath:logback-broken.xml'");
 			assertThat(this.output).contains("ConsolAppender");
@@ -237,7 +238,7 @@ class LoggingApplicationListenerTests {
 	void addLogFileProperty() {
 		addPropertiesToEnvironment(this.context, "logging.config=classpath:nondefault.xml",
 				"logging.file.name=" + this.logFile);
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		Log logger = LogFactory.getLog(LoggingApplicationListenerTests.class);
 		String existingOutput = this.output.toString();
 		logger.info("Hello world");
@@ -249,7 +250,7 @@ class LoggingApplicationListenerTests {
 	void addLogFilePropertyWithDefault() {
 		assertThat(this.logFile).doesNotExist();
 		addPropertiesToEnvironment(this.context, "logging.file.name=" + this.logFile);
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		Log logger = LogFactory.getLog(LoggingApplicationListenerTests.class);
 		logger.info("Hello world");
 		assertThat(this.logFile).isFile();
@@ -260,7 +261,7 @@ class LoggingApplicationListenerTests {
 	void addLogPathProperty() {
 		addPropertiesToEnvironment(this.context, "logging.config=classpath:nondefault.xml",
 				"logging.file.path=" + this.tempDir);
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		Log logger = LogFactory.getLog(LoggingApplicationListenerTests.class);
 		String existingOutput = this.output.toString();
 		logger.info("Hello world");
@@ -271,7 +272,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void parseDebugArg() {
 		addPropertiesToEnvironment(this.context, "debug");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.trace("testattrace");
 		assertThat(this.output).contains("testatdebug");
@@ -281,19 +282,22 @@ class LoggingApplicationListenerTests {
 	@Test
 	void parseDebugArgExpandGroups() {
 		addPropertiesToEnvironment(this.context, "debug");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.loggerContext.getLogger("org.springframework.boot.actuate.endpoint.web").debug("testdebugwebgroup");
 		this.loggerContext.getLogger("org.hibernate.SQL").debug("testdebugsqlgroup");
 		assertThat(this.output).contains("testdebugwebgroup");
 		assertThat(this.output).contains("testdebugsqlgroup");
 		LoggerGroups loggerGroups = (LoggerGroups) ReflectionTestUtils.getField(this.listener, "loggerGroups");
-		assertThat(loggerGroups.get("web").getConfiguredLevel()).isEqualTo(LogLevel.DEBUG);
+		assertThat(loggerGroups).isNotNull();
+		LoggerGroup loggerGroup = loggerGroups.get("web");
+		assertThat(loggerGroup).isNotNull();
+		assertThat(loggerGroup.getConfiguredLevel()).isEqualTo(LogLevel.DEBUG);
 	}
 
 	@Test
 	void parseTraceArg() {
 		addPropertiesToEnvironment(this.context, "trace");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.trace("testattrace");
 		assertThat(this.output).contains("testatdebug");
@@ -312,7 +316,7 @@ class LoggingApplicationListenerTests {
 
 	private void disableDebugTraceArg(String... environment) {
 		addPropertiesToEnvironment(this.context, environment);
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.trace("testattrace");
 		assertThat(this.output).doesNotContain("testatdebug");
@@ -322,7 +326,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void parseLevels() {
 		addPropertiesToEnvironment(this.context, "logging.level.org.springframework.boot=TRACE");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.trace("testattrace");
 		assertThat(this.output).contains("testatdebug");
@@ -332,7 +336,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void parseLevelsCaseInsensitive() {
 		addPropertiesToEnvironment(this.context, "logging.level.org.springframework.boot=TrAcE");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.trace("testattrace");
 		assertThat(this.output).contains("testatdebug");
@@ -342,7 +346,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void parseLevelsTrimsWhitespace() {
 		addPropertiesToEnvironment(this.context, "logging.level.org.springframework.boot= trace ");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.trace("testattrace");
 		assertThat(this.output).contains("testatdebug");
@@ -352,7 +356,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void parseLevelsWithPlaceholder() {
 		addPropertiesToEnvironment(this.context, "foo=TRACE", "logging.level.org.springframework.boot=${foo}");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.trace("testattrace");
 		assertThat(this.output).contains("testatdebug");
@@ -364,13 +368,13 @@ class LoggingApplicationListenerTests {
 		this.logger.setLevel(Level.INFO);
 		addPropertiesToEnvironment(this.context, "logging.level.org.springframework.boot=GARBAGE");
 		assertThatExceptionOfType(BindException.class)
-			.isThrownBy(() -> this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader()));
+			.isThrownBy(() -> this.listener.initialize(this.context.getEnvironment(), getClassLoader()));
 	}
 
 	@Test
 	void parseLevelsNone() {
 		addPropertiesToEnvironment(this.context, "logging.level.org.springframework.boot=OFF");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.error("testaterror");
 		assertThat(this.output).doesNotContain("testatdebug").doesNotContain("testaterror");
@@ -379,7 +383,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void parseLevelsMapsFalseToOff() {
 		addPropertiesToEnvironment(this.context, "logging.level.org.springframework.boot=false");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		this.logger.error("testaterror");
 		assertThat(this.output).doesNotContain("testatdebug").doesNotContain("testaterror");
@@ -389,7 +393,7 @@ class LoggingApplicationListenerTests {
 	void parseArgsDisabled() {
 		this.listener.setParseArgs(false);
 		addPropertiesToEnvironment(this.context, "debug");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		assertThat(this.output).doesNotContain("testatdebug");
 	}
@@ -400,7 +404,7 @@ class LoggingApplicationListenerTests {
 		this.listener.setParseArgs(false);
 		multicastEvent(new ApplicationStartingEvent(this.bootstrapContext, this.springApplication,
 				new String[] { "--debug" }));
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		assertThat(this.output).doesNotContain("testatdebug");
 	}
@@ -414,7 +418,7 @@ class LoggingApplicationListenerTests {
 
 	@Test
 	void defaultExceptionConversionWord() {
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.info("Hello world", new RuntimeException("Wrapper", new RuntimeException("Expected")));
 		assertThat(this.output).contains("Hello world");
 		assertThat(this.output).doesNotContain("Wrapped by: java.lang.RuntimeException: Wrapper");
@@ -423,7 +427,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void overrideExceptionConversionWord() {
 		addPropertiesToEnvironment(this.context, "logging.exceptionConversionWord=%rEx");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.info("Hello world", new RuntimeException("Wrapper", new RuntimeException("Expected")));
 		assertThat(this.output).contains("Hello world");
 		assertThat(this.output).contains("Wrapped by: java.lang.RuntimeException: Wrapper");
@@ -434,13 +438,16 @@ class LoggingApplicationListenerTests {
 		TestLoggingApplicationListener listener = new TestLoggingApplicationListener();
 		Object registered = ReflectionTestUtils.getField(listener, TestLoggingApplicationListener.class,
 				"shutdownHookRegistered");
+		assertThat(registered).isNotNull();
 		((AtomicBoolean) registered).set(false);
 		System.setProperty(LoggingSystem.class.getName(), TestShutdownHandlerLoggingSystem.class.getName());
 		multicastEvent(listener, new ApplicationStartingEvent(this.bootstrapContext, new SpringApplication(), NO_ARGS));
-		listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		listener.initialize(this.context.getEnvironment(), getClassLoader());
 		assertThat(listener.shutdownHook).isNotNull();
 		listener.shutdownHook.run();
-		assertThat(TestShutdownHandlerLoggingSystem.shutdownLatch.await(30, TimeUnit.SECONDS)).isTrue();
+		CountDownLatch shutdownLatch = TestShutdownHandlerLoggingSystem.shutdownLatch;
+		assertThat(shutdownLatch).isNotNull();
+		assertThat(shutdownLatch.await(30, TimeUnit.SECONDS)).isTrue();
 	}
 
 	@Test
@@ -448,11 +455,12 @@ class LoggingApplicationListenerTests {
 		TestLoggingApplicationListener listener = new TestLoggingApplicationListener();
 		Object registered = ReflectionTestUtils.getField(listener, TestLoggingApplicationListener.class,
 				"shutdownHookRegistered");
+		assertThat(registered).isNotNull();
 		((AtomicBoolean) registered).set(false);
 		System.setProperty(LoggingSystem.class.getName(), TestShutdownHandlerLoggingSystem.class.getName());
 		addPropertiesToEnvironment(this.context, "logging.register_shutdown_hook=false");
 		multicastEvent(listener, new ApplicationStartingEvent(this.bootstrapContext, new SpringApplication(), NO_ARGS));
-		listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		listener.initialize(this.context.getEnvironment(), getClassLoader());
 		assertThat(listener.shutdownHook).isNull();
 	}
 
@@ -462,6 +470,7 @@ class LoggingApplicationListenerTests {
 		multicastEvent(new ApplicationStartingEvent(this.bootstrapContext, this.springApplication, new String[0]));
 		TestCleanupLoggingSystem loggingSystem = (TestCleanupLoggingSystem) ReflectionTestUtils.getField(this.listener,
 				"loggingSystem");
+		assertThat(loggingSystem).isNotNull();
 		assertThat(loggingSystem.cleanedUp).isFalse();
 		multicastEvent(new ContextClosedEvent(this.context));
 		assertThat(loggingSystem.cleanedUp).isTrue();
@@ -473,6 +482,7 @@ class LoggingApplicationListenerTests {
 		multicastEvent(new ApplicationStartingEvent(this.bootstrapContext, this.springApplication, new String[0]));
 		TestCleanupLoggingSystem loggingSystem = (TestCleanupLoggingSystem) ReflectionTestUtils.getField(this.listener,
 				"loggingSystem");
+		assertThat(loggingSystem).isNotNull();
 		assertThat(loggingSystem.cleanedUp).isFalse();
 		GenericApplicationContext childContext = new GenericApplicationContext();
 		childContext.setParent(this.context);
@@ -489,7 +499,7 @@ class LoggingApplicationListenerTests {
 				"logging.file.name=" + this.logFile, "logging.file.path=path", "logging.pattern.console=console",
 				"logging.pattern.file=file", "logging.pattern.level=level", "logging.pattern.correlation=correlation",
 				"logging.pattern.rolling-file-name=my.log.%d{yyyyMMdd}.%i.gz");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		assertThat(getSystemProperty(LoggingSystemProperty.CONSOLE_PATTERN)).isEqualTo("console");
 		assertThat(getSystemProperty(LoggingSystemProperty.FILE_PATTERN)).isEqualTo("file");
 		assertThat(getSystemProperty(LoggingSystemProperty.EXCEPTION_CONVERSION_WORD)).isEqualTo("conversion");
@@ -503,14 +513,14 @@ class LoggingApplicationListenerTests {
 	void environmentPropertiesIgnoreUnresolvablePlaceholders() {
 		// gh-7719
 		addPropertiesToEnvironment(this.context, "logging.pattern.console=console ${doesnotexist}");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		assertThat(getSystemProperty(LoggingSystemProperty.CONSOLE_PATTERN)).isEqualTo("console ${doesnotexist}");
 	}
 
 	@Test
 	void environmentPropertiesResolvePlaceholders() {
 		addPropertiesToEnvironment(this.context, "logging.pattern.console=console ${pid}");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		assertThat(getSystemProperty(LoggingSystemProperty.CONSOLE_PATTERN))
 			.isEqualTo(this.context.getEnvironment().getProperty("logging.pattern.console"));
 	}
@@ -518,7 +528,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void logFilePropertiesCanReferenceSystemProperties() {
 		addPropertiesToEnvironment(this.context, "logging.file.name=" + this.tempDir + "${PID}.log");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		assertThat(getSystemProperty(LoggingSystemProperty.LOG_FILE))
 			.isEqualTo(this.tempDir + new ApplicationPid().toString() + ".log");
 	}
@@ -529,6 +539,7 @@ class LoggingApplicationListenerTests {
 		multicastEvent(new ApplicationStartingEvent(this.bootstrapContext, this.springApplication, new String[0]));
 		TestCleanupLoggingSystem loggingSystem = (TestCleanupLoggingSystem) ReflectionTestUtils.getField(this.listener,
 				"loggingSystem");
+		assertThat(loggingSystem).isNotNull();
 		assertThat(loggingSystem.cleanedUp).isFalse();
 		multicastEvent(new ApplicationFailedEvent(this.springApplication, new String[0],
 				new GenericApplicationContext(), new Exception()));
@@ -547,6 +558,7 @@ class LoggingApplicationListenerTests {
 			.get();
 		TestCleanupLoggingSystem loggingSystem = (TestCleanupLoggingSystem) ReflectionTestUtils.getField(listener,
 				"loggingSystem");
+		assertThat(loggingSystem).isNotNull();
 		assertThat(loggingSystem.cleanedUp).isFalse();
 		WebServerStyleLifecycle lifecycle = context.getBean(WebServerStyleLifecycle.class);
 		AtomicBoolean called = new AtomicBoolean();
@@ -567,7 +579,7 @@ class LoggingApplicationListenerTests {
 		propertySources
 			.addFirst(new MapPropertySource("test1", Collections.singletonMap("logging.level.ROOT", "DEBUG")));
 		propertySources.addLast(new MapPropertySource("test2", Collections.singletonMap("logging.level.root", "WARN")));
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		this.logger.debug("testatdebug");
 		assertThat(this.output).contains("testatdebug");
 	}
@@ -575,7 +587,7 @@ class LoggingApplicationListenerTests {
 	@Test
 	void loggingGroupsDefaultsAreApplied() {
 		addPropertiesToEnvironment(this.context, "logging.level.web=TRACE");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		assertTraceEnabled("org.springframework.core", false);
 		assertTraceEnabled("org.springframework.core.codec", true);
 		assertTraceEnabled("org.springframework.http", true);
@@ -588,12 +600,18 @@ class LoggingApplicationListenerTests {
 	void loggingGroupsCanBeDefined() {
 		addPropertiesToEnvironment(this.context, "logging.group.foo=com.foo.bar,com.foo.baz",
 				"logging.level.foo=TRACE");
-		this.listener.initialize(this.context.getEnvironment(), this.context.getClassLoader());
+		this.listener.initialize(this.context.getEnvironment(), getClassLoader());
 		assertTraceEnabled("com.foo", false);
 		assertTraceEnabled("com.foo.bar", true);
 		assertTraceEnabled("com.foo.baz", true);
 	}
 
+	private ClassLoader getClassLoader() {
+		ClassLoader classLoader = this.context.getClassLoader();
+		assertThat(classLoader).isNotNull();
+		return classLoader;
+	}
+
 	private String getSystemProperty(LoggingSystemProperty property) {
 		return System.getProperty(property.getEnvironmentVariableName());
 	}
@@ -636,7 +654,7 @@ class LoggingApplicationListenerTests {
 
 	static class TestShutdownHandlerLoggingSystem extends AbstractLoggingSystem {
 
-		private static CountDownLatch shutdownLatch;
+		private static @Nullable CountDownLatch shutdownLatch;
 
 		TestShutdownHandlerLoggingSystem(ClassLoader classLoader) {
 			super(classLoader);
@@ -649,38 +667,42 @@ class LoggingApplicationListenerTests {
 		}
 
 		@Override
-		protected void loadDefaults(LoggingInitializationContext initializationContext, LogFile logFile) {
+		protected void loadDefaults(LoggingInitializationContext initializationContext, @Nullable LogFile logFile) {
 		}
 
 		@Override
 		protected void loadConfiguration(LoggingInitializationContext initializationContext, String location,
-				LogFile logFile) {
+				@Nullable LogFile logFile) {
 		}
 
 		@Override
-		public void setLogLevel(String loggerName, LogLevel level) {
+		public void setLogLevel(@Nullable String loggerName, @Nullable LogLevel level) {
 		}
 
 		@Override
 		public List<LoggerConfiguration> getLoggerConfigurations() {
-			return null;
+			return Collections.emptyList();
 		}
 
 		@Override
-		public LoggerConfiguration getLoggerConfiguration(String loggerName) {
+		public @Nullable LoggerConfiguration getLoggerConfiguration(String loggerName) {
 			return null;
 		}
 
 		@Override
 		public Runnable getShutdownHandler() {
-			return () -> TestShutdownHandlerLoggingSystem.shutdownLatch.countDown();
+			return () -> {
+				CountDownLatch shutdownLatch = TestShutdownHandlerLoggingSystem.shutdownLatch;
+				assertThat(shutdownLatch).isNotNull();
+				shutdownLatch.countDown();
+			};
 		}
 
 	}
 
 	static class TestLoggingApplicationListener extends LoggingApplicationListener {
 
-		private Runnable shutdownHook;
+		private @Nullable Runnable shutdownHook;
 
 		@Override
 		void registerShutdownHook(Runnable shutdownHook) {
@@ -701,16 +723,16 @@ class LoggingApplicationListenerTests {
 		}
 
 		@Override
-		public void setLogLevel(String loggerName, LogLevel level) {
+		public void setLogLevel(@Nullable String loggerName, @Nullable LogLevel level) {
 		}
 
 		@Override
 		public List<LoggerConfiguration> getLoggerConfigurations() {
-			return null;
+			return Collections.emptyList();
 		}
 
 		@Override
-		public LoggerConfiguration getLoggerConfiguration(String loggerName) {
+		public @Nullable LoggerConfiguration getLoggerConfiguration(String loggerName) {
 			return null;
 		}
 
@@ -732,22 +754,22 @@ class LoggingApplicationListenerTests {
 		}
 
 		@Override
-		public void initialize(LoggingInitializationContext initializationContext, String configLocation,
-				LogFile logFile) {
+		public void initialize(LoggingInitializationContext initializationContext, @Nullable String configLocation,
+				@Nullable LogFile logFile) {
 			throw new Error("Deliberately broken");
 		}
 
 		@Override
-		public void setLogLevel(String loggerName, LogLevel level) {
+		public void setLogLevel(@Nullable String loggerName, @Nullable LogLevel level) {
 		}
 
 		@Override
 		public List<LoggerConfiguration> getLoggerConfigurations() {
-			return null;
+			return Collections.emptyList();
 		}
 
 		@Override
-		public LoggerConfiguration getLoggerConfiguration(String loggerName) {
+		public @Nullable LoggerConfiguration getLoggerConfiguration(String loggerName) {
 			return null;
 		}
 
@@ -763,7 +785,7 @@ class LoggingApplicationListenerTests {
 
 		private volatile boolean running;
 
-		Runnable onStop;
+		@Nullable Runnable onStop;
 
 		@Override
 		public void start() {
@@ -773,7 +795,9 @@ class LoggingApplicationListenerTests {
 		@Override
 		public void stop() {
 			this.running = false;
-			this.onStop.run();
+			if (this.onStop != null) {
+				this.onStop.run();
+			}
 		}
 
 		@Override

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests.java

@@ -21,6 +21,7 @@ import java.util.stream.Stream;
 import org.assertj.core.api.AbstractAssert;
 import org.assertj.core.api.AssertProvider;
 import org.assertj.core.error.BasicErrorMessageFactory;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.aot.hint.TypeHint;
@@ -28,6 +29,7 @@ import org.springframework.aot.hint.TypeReference;
 import org.springframework.aot.test.generate.TestGenerationContext;
 import org.springframework.beans.factory.aot.AotServices;
 import org.springframework.beans.factory.aot.BeanFactoryInitializationAotProcessor;
+import org.springframework.beans.factory.aot.BeanFactoryInitializationCode;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
 import org.springframework.boot.context.properties.ConfigurationPropertiesBeanFactoryInitializationAotProcessor.ConfigurationPropertiesReflectionHintsContribution;
@@ -38,6 +40,7 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
 
 /**
  * Tests for {@link ConfigurationPropertiesBeanFactoryInitializationAotProcessor}.
@@ -67,6 +70,7 @@ class ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests {
 		DefaultListableBeanFactory beanFactory = new DefaultListableBeanFactory();
 		beanFactory.registerSingleton("test", new SampleProperties());
 		ConfigurationPropertiesReflectionHintsContribution contribution = process(beanFactory);
+		assertThat(contribution).isNotNull();
 		assertThat(singleBindable(contribution)).hasBindMethod(BindMethod.JAVA_BEAN).hasType(SampleProperties.class);
 		assertThat(typeHints(contribution).map(TypeHint::getType))
 			.containsExactly(TypeReference.of(SampleProperties.class));
@@ -75,6 +79,7 @@ class ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests {
 	@Test
 	void javaBeanConfigurationPropertiesBindAsJavaBean() {
 		ConfigurationPropertiesReflectionHintsContribution contribution = process(EnableJavaBeanProperties.class);
+		assertThat(contribution).isNotNull();
 		assertThat(singleBindable(contribution)).hasBindMethod(BindMethod.JAVA_BEAN).hasType(JavaBeanProperties.class);
 		assertThat(typeHints(contribution).map(TypeHint::getType))
 			.containsExactly(TypeReference.of(JavaBeanProperties.class));
@@ -84,6 +89,7 @@ class ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests {
 	void constructorBindingConfigurationPropertiesBindAsValueObject() {
 		ConfigurationPropertiesReflectionHintsContribution contribution = process(
 				EnableConstructorBindingProperties.class);
+		assertThat(contribution).isNotNull();
 		assertThat(singleBindable(contribution)).hasBindMethod(BindMethod.VALUE_OBJECT)
 			.hasType(ConstructorBindingProperties.class);
 		assertThat(typeHints(contribution).map(TypeHint::getType))
@@ -94,6 +100,7 @@ class ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests {
 	void possibleConstructorBindingPropertiesDefinedThroughBeanMethodBindAsJavaBean() {
 		ConfigurationPropertiesReflectionHintsContribution contribution = process(
 				PossibleConstructorBindingPropertiesBeanMethodConfiguration.class);
+		assertThat(contribution).isNotNull();
 		assertThat(singleBindable(contribution)).hasBindMethod(BindMethod.JAVA_BEAN)
 			.hasType(PossibleConstructorBindingProperties.class);
 		assertThat(typeHints(contribution).map(TypeHint::getType))
@@ -104,6 +111,7 @@ class ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests {
 	void possibleConstructorBindingPropertiesDefinedThroughEnabledAnnotationBindAsValueObject() {
 		ConfigurationPropertiesReflectionHintsContribution contribution = process(
 				EnablePossibleConstructorBindingProperties.class);
+		assertThat(contribution).isNotNull();
 		assertThat(singleBindable(contribution)).hasBindMethod(BindMethod.VALUE_OBJECT)
 			.hasType(PossibleConstructorBindingProperties.class);
 		assertThat(typeHints(contribution).map(TypeHint::getType))
@@ -112,17 +120,18 @@ class ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests {
 
 	private Stream<TypeHint> typeHints(ConfigurationPropertiesReflectionHintsContribution contribution) {
 		TestGenerationContext generationContext = new TestGenerationContext();
-		contribution.applyTo(generationContext, null);
+		contribution.applyTo(generationContext, mock(BeanFactoryInitializationCode.class));
 		return generationContext.getRuntimeHints().reflection().typeHints();
 	}
 
-	private ConfigurationPropertiesReflectionHintsContribution process(Class<?> config) {
+	private @Nullable ConfigurationPropertiesReflectionHintsContribution process(Class<?> config) {
 		try (AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(config)) {
 			return process(context.getBeanFactory());
 		}
 	}
 
-	private ConfigurationPropertiesReflectionHintsContribution process(ConfigurableListableBeanFactory beanFactory) {
+	private @Nullable ConfigurationPropertiesReflectionHintsContribution process(
+			ConfigurableListableBeanFactory beanFactory) {
 		return this.processor.processAheadOfTime(beanFactory);
 	}
 
@@ -144,13 +153,13 @@ class ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests {
 	@ConfigurationProperties("java-bean")
 	static class JavaBeanProperties {
 
-		private String value;
+		private @Nullable String value;
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
-		void setValue(String value) {
+		void setValue(@Nullable String value) {
 			this.value = value;
 		}
 
@@ -195,17 +204,17 @@ class ConfigurationPropertiesBeanFactoryInitializationAotProcessorTests {
 	@ConfigurationProperties("possible-constructor-binding")
 	static class PossibleConstructorBindingProperties {
 
-		private String value;
+		private @Nullable String value;
 
 		PossibleConstructorBindingProperties(String arg) {
 
 		}
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
-		void setValue(String value) {
+		void setValue(@Nullable String value) {
 			this.value = value;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBeanRegistrationAotProcessorTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.context.properties;
 import java.util.Arrays;
 import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.aot.test.generate.TestGenerationContext;
@@ -81,7 +82,7 @@ class ConfigurationPropertiesBeanRegistrationAotProcessorTests {
 		assertThat(contribution).isNotNull();
 	}
 
-	private BeanRegistrationAotContribution process(Class<?> type) {
+	private @Nullable BeanRegistrationAotContribution process(Class<?> type) {
 		ConfigurationPropertiesBeanRegistrar beanRegistrar = new ConfigurationPropertiesBeanRegistrar(this.beanFactory);
 		beanRegistrar.register(type);
 		RegisteredBean registeredBean = RegisteredBean.of(this.beanFactory,
@@ -177,13 +178,13 @@ class ConfigurationPropertiesBeanRegistrationAotProcessorTests {
 	@ConfigurationProperties("test")
 	public static class JavaBeanSampleBean {
 
-		private String name;
+		private @Nullable String name;
 
-		public String getName() {
+		public @Nullable String getName() {
 			return this.name;
 		}
 
-		public void setName(String name) {
+		public void setName(@Nullable String name) {
 			this.name = name;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBeanTests.java

@@ -22,6 +22,7 @@ import java.util.Map;
 import net.bytebuddy.ByteBuddy;
 import net.bytebuddy.ClassFileVersion;
 import net.bytebuddy.description.annotation.AnnotationDescription;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.function.ThrowingConsumer;
 
@@ -60,18 +61,21 @@ class ConfigurationPropertiesBeanTests {
 			Map<String, ConfigurationPropertiesBean> all = ConfigurationPropertiesBean.getAll(context);
 			assertThat(all).containsOnlyKeys("annotatedComponent", "annotatedBean", ValueObject.class.getName());
 			ConfigurationPropertiesBean component = all.get("annotatedComponent");
+			assertThat(component).isNotNull();
 			assertThat(component.getName()).isEqualTo("annotatedComponent");
 			assertThat(component.getInstance()).isInstanceOf(AnnotatedComponent.class);
 			assertThat(component.getAnnotation()).isNotNull();
 			assertThat(component.getType()).isEqualTo(AnnotatedComponent.class);
 			assertThat(component.asBindTarget().getBindMethod()).isEqualTo(BindMethod.JAVA_BEAN);
 			ConfigurationPropertiesBean bean = all.get("annotatedBean");
+			assertThat(bean).isNotNull();
 			assertThat(bean.getName()).isEqualTo("annotatedBean");
 			assertThat(bean.getInstance()).isInstanceOf(AnnotatedBean.class);
 			assertThat(bean.getType()).isEqualTo(AnnotatedBean.class);
 			assertThat(bean.getAnnotation()).isNotNull();
 			assertThat(bean.asBindTarget().getBindMethod()).isEqualTo(BindMethod.JAVA_BEAN);
 			ConfigurationPropertiesBean valueObject = all.get(ValueObject.class.getName());
+			assertThat(valueObject).isNotNull();
 			assertThat(valueObject.getName()).isEqualTo(ValueObject.class.getName());
 			assertThat(valueObject.getInstance()).isInstanceOf(ValueObject.class);
 			assertThat(valueObject.getType()).isEqualTo(ValueObject.class);
@@ -157,6 +161,7 @@ class ConfigurationPropertiesBeanTests {
 	@Test
 	void getWhenHasFactoryMethodBindsUsingMethodReturnType() throws Throwable {
 		get(NonAnnotatedGenericBeanConfiguration.class, "nonAnnotatedGenericBean", (propertiesBean) -> {
+			assertThat(propertiesBean).isNotNull();
 			assertThat(propertiesBean.getType()).isEqualTo(NonAnnotatedGenericBean.class);
 			assertThat(propertiesBean.asBindTarget().getBindMethod()).isEqualTo(BindMethod.JAVA_BEAN);
 			ResolvableType type = propertiesBean.asBindTarget().getType();
@@ -168,6 +173,7 @@ class ConfigurationPropertiesBeanTests {
 	@Test
 	void getWhenHasFactoryMethodWithoutAnnotationBindsUsingMethodType() throws Throwable {
 		get(AnnotatedGenericBeanConfiguration.class, "annotatedGenericBean", (propertiesBean) -> {
+			assertThat(propertiesBean).isNotNull();
 			assertThat(propertiesBean.getType()).isEqualTo(AnnotatedGenericBean.class);
 			assertThat(propertiesBean.asBindTarget().getBindMethod()).isEqualTo(BindMethod.JAVA_BEAN);
 			ResolvableType type = propertiesBean.asBindTarget().getType();
@@ -179,6 +185,7 @@ class ConfigurationPropertiesBeanTests {
 	@Test
 	void getWhenHasNoFactoryMethodBindsUsingObjectType() throws Throwable {
 		get(AnnotatedGenericComponent.class, "annotatedGenericComponent", (propertiesBean) -> {
+			assertThat(propertiesBean).isNotNull();
 			assertThat(propertiesBean.getType()).isEqualTo(AnnotatedGenericComponent.class);
 			assertThat(propertiesBean.asBindTarget().getBindMethod()).isEqualTo(BindMethod.JAVA_BEAN);
 			ResolvableType type = propertiesBean.asBindTarget().getType();
@@ -189,14 +196,18 @@ class ConfigurationPropertiesBeanTests {
 
 	@Test
 	void getWhenHasFactoryMethodAndBeanAnnotationFavorsFactoryMethod() throws Throwable {
-		get(AnnotatedBeanConfiguration.class, "annotatedBean",
-				(propertiesBean) -> assertThat(propertiesBean.getAnnotation().prefix()).isEqualTo("factory"));
+		get(AnnotatedBeanConfiguration.class, "annotatedBean", (propertiesBean) -> {
+			assertThat(propertiesBean).isNotNull();
+			assertThat(propertiesBean.getAnnotation().prefix()).isEqualTo("factory");
+		});
 	}
 
 	@Test
 	void getWhenHasValidatedBeanBindsWithBeanAnnotation() throws Throwable {
 		get(ValidatedBeanConfiguration.class, "validatedBean", (propertiesBean) -> {
+			assertThat(propertiesBean).isNotNull();
 			Validated validated = propertiesBean.asBindTarget().getAnnotation(Validated.class);
+			assertThat(validated).isNotNull();
 			assertThat(validated.value()).containsExactly(BeanGroup.class);
 		});
 	}
@@ -204,7 +215,9 @@ class ConfigurationPropertiesBeanTests {
 	@Test
 	void getWhenHasValidatedFactoryMethodBindsWithFactoryMethodAnnotation() throws Throwable {
 		get(ValidatedMethodConfiguration.class, "annotatedBean", (propertiesBean) -> {
+			assertThat(propertiesBean).isNotNull();
 			Validated validated = propertiesBean.asBindTarget().getAnnotation(Validated.class);
+			assertThat(validated).isNotNull();
 			assertThat(validated.value()).containsExactly(FactoryMethodGroup.class);
 		});
 	}
@@ -212,7 +225,9 @@ class ConfigurationPropertiesBeanTests {
 	@Test
 	void getWhenHasValidatedBeanAndFactoryMethodBindsWithFactoryMethodAnnotation() throws Throwable {
 		get(ValidatedMethodAndBeanConfiguration.class, "validatedBean", (propertiesBean) -> {
+			assertThat(propertiesBean).isNotNull();
 			Validated validated = propertiesBean.asBindTarget().getAnnotation(Validated.class);
+			assertThat(validated).isNotNull();
 			assertThat(validated.value()).containsExactly(FactoryMethodGroup.class);
 		});
 	}
@@ -336,18 +351,18 @@ class ConfigurationPropertiesBeanTests {
 		assertThat(bindType).isEqualTo(BindMethod.JAVA_BEAN);
 	}
 
-	private void get(Class<?> configuration, String beanName, ThrowingConsumer<ConfigurationPropertiesBean> consumer)
-			throws Throwable {
+	private void get(Class<?> configuration, String beanName,
+			ThrowingConsumer<@Nullable ConfigurationPropertiesBean> consumer) throws Throwable {
 		get(configuration, beanName, true, consumer);
 	}
 
 	private void getWithoutBeanMetadataCaching(Class<?> configuration, String beanName,
-			ThrowingConsumer<ConfigurationPropertiesBean> consumer) throws Throwable {
+			ThrowingConsumer<@Nullable ConfigurationPropertiesBean> consumer) throws Throwable {
 		get(configuration, beanName, false, consumer);
 	}
 
 	private void get(Class<?> configuration, String beanName, boolean cacheBeanMetadata,
-			ThrowingConsumer<ConfigurationPropertiesBean> consumer) throws Throwable {
+			ThrowingConsumer<@Nullable ConfigurationPropertiesBean> consumer) throws Throwable {
 		try (AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext()) {
 			context.getBeanFactory().setCacheBeanMetadata(cacheBeanMetadata);
 			context.register(configuration);

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindExceptionTests.java

@@ -36,6 +36,7 @@ class ConfigurationPropertiesBindExceptionTests {
 		ApplicationContext applicationContext = new AnnotationConfigApplicationContext(Example.class);
 		ConfigurationPropertiesBean bean = ConfigurationPropertiesBean.get(applicationContext,
 				applicationContext.getBean(Example.class), "example");
+		assertThat(bean).isNotNull();
 		ConfigurationPropertiesBindException exception = new ConfigurationPropertiesBindException(bean,
 				new IllegalStateException());
 		assertThat(exception.getMessage()).isEqualTo("Error creating bean with name 'example': "

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesBindHandlerAdvisorTests.java

@@ -20,6 +20,7 @@ import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.TreeMap;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 
@@ -57,9 +58,11 @@ class ConfigurationPropertiesBindHandlerAdvisorTests {
 				"foo.bar.bindings.output.destination=d2");
 		BindingServiceProperties properties = this.context.getBean(BindingServiceProperties.class);
 		BindingProperties input = properties.getBindings().get("input");
+		assertThat(input).isNotNull();
 		assertThat(input.getDestination()).isEqualTo("d1");
 		assertThat(input.getContentType()).isEqualTo("text/xml");
 		BindingProperties output = properties.getBindings().get("output");
+		assertThat(output).isNotNull();
 		assertThat(output.getDestination()).isEqualTo("d2");
 		assertThat(output.getContentType()).isEqualTo("application/json");
 	}
@@ -71,9 +74,11 @@ class ConfigurationPropertiesBindHandlerAdvisorTests {
 				"foo.bar.bindings.output.destination=d2");
 		BindingServiceProperties properties = this.context.getBean(BindingServiceProperties.class);
 		BindingProperties input = properties.getBindings().get("input");
+		assertThat(input).isNotNull();
 		assertThat(input.getDestination()).isEqualTo("d1");
 		assertThat(input.getContentType()).isEqualTo("text/xml");
 		BindingProperties output = properties.getBindings().get("output");
+		assertThat(output).isNotNull();
 		assertThat(output.getDestination()).isEqualTo("d2");
 		assertThat(output.getContentType()).isEqualTo("text/plain");
 	}
@@ -124,7 +129,8 @@ class ConfigurationPropertiesBindHandlerAdvisorTests {
 		}
 
 		@Override
-		public <T> Bindable<T> onStart(ConfigurationPropertyName name, Bindable<T> target, BindContext context) {
+		public <T> @Nullable Bindable<T> onStart(ConfigurationPropertyName name, Bindable<T> target,
+				BindContext context) {
 			ConfigurationPropertyName defaultName = getDefaultName(name);
 			if (defaultName != null) {
 				BindResult<T> result = context.getBinder().bind(defaultName, target);
@@ -135,7 +141,7 @@ class ConfigurationPropertiesBindHandlerAdvisorTests {
 			return super.onStart(name, target, context);
 		}
 
-		private ConfigurationPropertyName getDefaultName(ConfigurationPropertyName name) {
+		private @Nullable ConfigurationPropertyName getDefaultName(ConfigurationPropertyName name) {
 			for (Map.Entry<ConfigurationPropertyName, ConfigurationPropertyName> mapping : this.mappings.entrySet()) {
 				ConfigurationPropertyName from = mapping.getKey();
 				ConfigurationPropertyName to = mapping.getValue();
@@ -161,15 +167,15 @@ class ConfigurationPropertiesBindHandlerAdvisorTests {
 
 	static class BindingProperties {
 
-		private String destination;
+		private @Nullable String destination;
 
 		private String contentType = "application/json";
 
-		String getDestination() {
+		@Nullable String getDestination() {
 			return this.destination;
 		}
 
-		void setDestination(String destination) {
+		void setDestination(@Nullable String destination) {
 			this.destination = destination;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesScanTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.context.properties;
 import java.io.IOException;
 import java.util.Objects;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
@@ -151,7 +152,7 @@ class ConfigurationPropertiesScanTests {
 		}
 
 		@Override
-		public boolean equals(Object o) {
+		public boolean equals(@Nullable Object o) {
 			return (this == o);
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTestBeanTests.java

@@ -37,6 +37,7 @@ import static org.assertj.core.api.Assertions.assertThat;
 class ConfigurationPropertiesTestBeanTests {
 
 	@TestBean
+	@SuppressWarnings("NullAway.Init")
 	private ImmutableProperties properties;
 
 	@Autowired

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConfigurationPropertiesTests.java

@@ -38,6 +38,7 @@ import jakarta.annotation.PostConstruct;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.NotEmpty;
 import jakarta.validation.constraints.NotNull;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
@@ -56,6 +57,7 @@ import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.BeanDefinitionRegistry;
 import org.springframework.beans.factory.support.RootBeanDefinition;
 import org.springframework.boot.SpringApplication;
+import org.springframework.boot.context.properties.ConfigurationPropertiesTests.JavaBeanNestedConstructorBindingProperties.Nested;
 import org.springframework.boot.context.properties.bind.BindException;
 import org.springframework.boot.context.properties.bind.ConstructorBinding;
 import org.springframework.boot.context.properties.bind.DefaultValue;
@@ -368,7 +370,9 @@ class ConfigurationPropertiesTests {
 	void loadShouldBindToJavaTimeDuration() {
 		load(BasicConfiguration.class, "duration=PT1M");
 		BasicProperties bean = this.context.getBean(BasicProperties.class);
-		assertThat(bean.getDuration().getSeconds()).isEqualTo(60);
+		Duration duration = bean.getDuration();
+		assertThat(duration).isNotNull();
+		assertThat(duration.getSeconds()).isEqualTo(60);
 	}
 
 	@Test
@@ -480,7 +484,9 @@ class ConfigurationPropertiesTests {
 	void loadShouldBindToMapWithNumericKey() {
 		load(MapWithNumericKeyProperties.class, "sample.properties.1.name=One");
 		MapWithNumericKeyProperties bean = this.context.getBean(MapWithNumericKeyProperties.class);
-		assertThat(bean.getProperties().get("1").name).isEqualTo("One");
+		BasicProperties one = bean.getProperties().get("1");
+		assertThat(one).isNotNull();
+		assertThat(one.name).isEqualTo("One");
 	}
 
 	@Test
@@ -491,8 +497,10 @@ class ConfigurationPropertiesTests {
 					Collections.singletonMap("TEST_MAP_FOO_BAR", "baz")));
 		load(WithComplexMapProperties.class);
 		WithComplexMapProperties bean = this.context.getBean(WithComplexMapProperties.class);
-		assertThat(bean.getMap()).containsOnlyKeys("foo");
-		assertThat(bean.getMap().get("foo")).containsOnly(entry("bar", "baz"));
+		Map<String, Map<String, String>> map = bean.getMap();
+		assertThat(map).isNotNull();
+		assertThat(map).containsOnlyKeys("foo");
+		assertThat(map.get("foo")).containsOnly(entry("bar", "baz"));
 	}
 
 	@Test
@@ -692,6 +700,7 @@ class ConfigurationPropertiesTests {
 	void loadShouldUseConverterBean() {
 		prepareConverterContext(PersonConverterConfiguration.class, PersonProperties.class);
 		Person person = this.context.getBean(PersonProperties.class).getPerson();
+		assertThat(person).isNotNull();
 		assertThat(person.firstName).isEqualTo("John");
 		assertThat(person.lastName).isEqualTo("Smith");
 	}
@@ -727,6 +736,7 @@ class ConfigurationPropertiesTests {
 		this.context.getEnvironment().getPropertySources().addLast(testProperties);
 		this.context.refresh();
 		Person person = this.context.getBean(PersonProperties.class).getPerson();
+		assertThat(person).isNotNull();
 		assertThat(person.firstName).isEqualTo("John");
 		assertThat(person.lastName).isEqualTo("Smith");
 	}
@@ -739,9 +749,13 @@ class ConfigurationPropertiesTests {
 		load(new Class<?>[] { PersonConverterConfiguration.class, PersonAndAlienProperties.class },
 				"test.person=John Smith", "test.alien=Alf Tanner");
 		PersonAndAlienProperties properties = this.context.getBean(PersonAndAlienProperties.class);
-		assertThat(properties.getPerson().firstName).isEqualTo("John");
-		assertThat(properties.getPerson().lastName).isEqualTo("Smith");
-		assertThat(properties.getAlien().name).isEqualTo("rennaT flA");
+		Person person = properties.getPerson();
+		assertThat(person).isNotNull();
+		assertThat(person.firstName).isEqualTo("John");
+		assertThat(person.lastName).isEqualTo("Smith");
+		Alien alien = properties.getAlien();
+		assertThat(alien).isNotNull();
+		assertThat(alien.name).isEqualTo("rennaT flA");
 	}
 
 	@Test
@@ -752,9 +766,13 @@ class ConfigurationPropertiesTests {
 		load(new Class<?>[] { AlienConverterConfiguration.class, PersonAndAlienProperties.class },
 				"test.person=John Smith", "test.alien=Alf Tanner");
 		PersonAndAlienProperties properties = this.context.getBean(PersonAndAlienProperties.class);
-		assertThat(properties.getPerson().firstName).isEqualTo("John");
-		assertThat(properties.getPerson().lastName).isEqualTo("Smith");
-		assertThat(properties.getAlien().name).isEqualTo("rennaT flA");
+		Person person = properties.getPerson();
+		assertThat(person).isNotNull();
+		assertThat(person.firstName).isEqualTo("John");
+		assertThat(person.lastName).isEqualTo("Smith");
+		Alien alien = properties.getAlien();
+		assertThat(alien).isNotNull();
+		assertThat(alien.name).isEqualTo("rennaT flA");
 	}
 
 	@Test // gh-38734
@@ -765,10 +783,14 @@ class ConfigurationPropertiesTests {
 		load(new Class<?>[] { AlienConverterConfiguration.class, PersonAndAliensProperties.class },
 				"test.person=John Smith", "test.aliens=Alf Tanner,Gilbert");
 		PersonAndAliensProperties properties = this.context.getBean(PersonAndAliensProperties.class);
-		assertThat(properties.getPerson().firstName).isEqualTo("John");
-		assertThat(properties.getPerson().lastName).isEqualTo("Smith");
-		assertThat(properties.getAliens().get(0).name).isEqualTo("rennaT flA");
-		assertThat(properties.getAliens().get(1).name).isEqualTo("trebliG");
+		Person person = properties.getPerson();
+		assertThat(person).isNotNull();
+		assertThat(person.firstName).isEqualTo("John");
+		assertThat(person.lastName).isEqualTo("Smith");
+		List<Alien> aliens = properties.getAliens();
+		assertThat(aliens).isNotNull();
+		assertThat(aliens.get(0).name).isEqualTo("rennaT flA");
+		assertThat(aliens.get(1).name).isEqualTo("trebliG");
 	}
 
 	@Test
@@ -782,6 +804,7 @@ class ConfigurationPropertiesTests {
 	void loadShouldUseGenericConverterBean() {
 		prepareConverterContext(GenericConverterConfiguration.class, PersonProperties.class);
 		Person person = this.context.getBean(PersonProperties.class).getPerson();
+		assertThat(person).isNotNull();
 		assertThat(person.firstName).isEqualTo("John");
 		assertThat(person.lastName).isEqualTo("Smith");
 	}
@@ -790,6 +813,7 @@ class ConfigurationPropertiesTests {
 	void loadShouldUseFormatterBean() {
 		prepareConverterContext(FormatterConfiguration.class, PersonProperties.class);
 		Person person = this.context.getBean(PersonProperties.class).getPerson();
+		assertThat(person).isNotNull();
 		assertThat(person.firstName).isEqualTo("John");
 		assertThat(person.lastName).isEqualTo("Smith");
 	}
@@ -875,8 +899,10 @@ class ConfigurationPropertiesTests {
 		this.context.getBeanFactory().registerCustomEditor(Person.class, PersonPropertyEditor.class);
 		load(PersonProperties.class, "test.person=boot,spring");
 		PersonProperties bean = this.context.getBean(PersonProperties.class);
-		assertThat(bean.getPerson().firstName).isEqualTo("spring");
-		assertThat(bean.getPerson().lastName).isEqualTo("boot");
+		Person person = bean.getPerson();
+		assertThat(person).isNotNull();
+		assertThat(person.firstName).isEqualTo("spring");
+		assertThat(person.lastName).isEqualTo("boot");
 	}
 
 	@Test
@@ -918,11 +944,18 @@ class ConfigurationPropertiesTests {
 		sources.addLast(new MapPropertySource("test", source));
 		load(WithIntegerMapProperties.class);
 		WithIntegerMapProperties bean = this.context.getBean(WithIntegerMapProperties.class);
-		Map<Integer, Foo> x = bean.getMap().get("x");
-		assertThat(x.get(-1).getA()).isEqualTo("baz");
-		assertThat(x.get(-1).getB()).isZero();
-		assertThat(x.get(1).getA()).isEqualTo("bar");
-		assertThat(x.get(1).getB()).isOne();
+		Map<String, Map<Integer, Foo>> map = bean.getMap();
+		assertThat(map).isNotNull();
+		Map<Integer, Foo> x = map.get("x");
+		assertThat(x).isNotNull();
+		Foo minus1 = x.get(-1);
+		assertThat(minus1).isNotNull();
+		assertThat(minus1.getA()).isEqualTo("baz");
+		assertThat(minus1.getB()).isZero();
+		Foo one = x.get(1);
+		assertThat(one).isNotNull();
+		assertThat(one.getA()).isEqualTo("bar");
+		assertThat(one.getB()).isOne();
 	}
 
 	@Test
@@ -1133,7 +1166,9 @@ class ConfigurationPropertiesTests {
 		load(JavaBeanNestedConstructorBindingPropertiesConfiguration.class);
 		JavaBeanNestedConstructorBindingProperties bean = this.context
 			.getBean(JavaBeanNestedConstructorBindingProperties.class);
-		assertThat(bean.getNested().getAge()).isEqualTo(5);
+		Nested nested = bean.getNested();
+		assertThat(nested).isNotNull();
+		assertThat(nested.getAge()).isEqualTo(5);
 	}
 
 	@Test
@@ -1156,7 +1191,9 @@ class ConfigurationPropertiesTests {
 		load(JavaBeanNonDefaultConstructorPropertiesConfiguration.class);
 		JavaBeanNonDefaultConstructorProperties bean = this.context
 			.getBean(JavaBeanNonDefaultConstructorProperties.class);
-		assertThat(bean.getNested().getAge()).isEqualTo(10);
+		JavaBeanNonDefaultConstructorProperties.Nested nested = bean.getNested();
+		assertThat(nested).isNotNull();
+		assertThat(nested.getAge()).isEqualTo(10);
 	}
 
 	@Test // gh-18652
@@ -1177,7 +1214,9 @@ class ConfigurationPropertiesTests {
 		load(ConstructorBindingWithOuterClassConstructorBoundConfiguration.class);
 		ConstructorBindingWithOuterClassConstructorBoundProperties bean = this.context
 			.getBean(ConstructorBindingWithOuterClassConstructorBoundProperties.class);
-		assertThat(bean.getNested().getOuter().getAge()).isEqualTo(5);
+		Outer outer = bean.getNested().getOuter();
+		assertThat(outer).isNotNull();
+		assertThat(outer.getAge()).isEqualTo(5);
 	}
 
 	@Test
@@ -1218,6 +1257,7 @@ class ConfigurationPropertiesTests {
 	void boundPropertiesShouldBeRecorded() {
 		load(NestedConfiguration.class, "name=foo", "nested.name=bar");
 		BoundConfigurationProperties bound = BoundConfigurationProperties.get(this.context);
+		assertThat(bound).isNotNull();
 		Set<ConfigurationPropertyName> keys = bound.getAll().keySet();
 		assertThat(keys.stream().map(ConfigurationPropertyName::toString)).contains("name", "nested.name");
 	}
@@ -1228,7 +1268,9 @@ class ConfigurationPropertiesTests {
 		load(WithCustomConverterAndObjectToObjectMethodConfiguration.class, "test.item=foo");
 		WithCustomConverterAndObjectToObjectMethodProperties bean = this.context
 			.getBean(WithCustomConverterAndObjectToObjectMethodProperties.class);
-		assertThat(bean.getItem().getValue()).isEqualTo("foo");
+		WithPublicObjectToObjectMethod item = bean.getItem();
+		assertThat(item).isNotNull();
+		assertThat(item.getValue()).isEqualTo("foo");
 	}
 
 	@Test // gh-33710
@@ -1465,15 +1507,15 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties
 	static class WithPostConstructConfiguration {
 
-		private String bar;
+		private @Nullable String bar;
 
 		private boolean initialized;
 
-		void setBar(String bar) {
+		void setBar(@Nullable String bar) {
 			this.bar = bar;
 		}
 
-		String getBar() {
+		@Nullable String getBar() {
 			return this.bar;
 		}
 
@@ -1564,13 +1606,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class PropertiesWithResource {
 
-		private Resource resource;
+		private @Nullable Resource resource;
 
-		Resource getResource() {
+		@Nullable Resource getResource() {
 			return this.resource;
 		}
 
-		void setResource(Resource resource) {
+		void setResource(@Nullable Resource resource) {
 			this.resource = resource;
 		}
 
@@ -1581,7 +1623,7 @@ class ConfigurationPropertiesTests {
 		static final String PREFIX = "test:/";
 
 		@Override
-		public Resource resolve(String location, ResourceLoader resourceLoader) {
+		public @Nullable Resource resolve(String location, ResourceLoader resourceLoader) {
 			if (location.startsWith(PREFIX)) {
 				String path = location.substring(PREFIX.length());
 				return new ClassPathResource(path);
@@ -1691,13 +1733,13 @@ class ConfigurationPropertiesTests {
 
 	static class AGenericClass<T> {
 
-		private T bar;
+		private @Nullable T bar;
 
-		T getBar() {
+		@Nullable T getBar() {
 			return this.bar;
 		}
 
-		void setBar(T bar) {
+		void setBar(@Nullable T bar) {
 			this.bar = bar;
 		}
 
@@ -1705,23 +1747,23 @@ class ConfigurationPropertiesTests {
 
 	static class PrototypeBean {
 
-		private String one;
+		private @Nullable String one;
 
-		private String two;
+		private @Nullable String two;
 
-		String getOne() {
+		@Nullable String getOne() {
 			return this.one;
 		}
 
-		void setOne(String one) {
+		void setOne(@Nullable String one) {
 			this.one = one;
 		}
 
-		String getTwo() {
+		@Nullable String getTwo() {
 			return this.two;
 		}
 
-		void setTwo(String two) {
+		void setTwo(@Nullable String two) {
 			this.two = two;
 		}
 
@@ -1737,7 +1779,7 @@ class ConfigurationPropertiesTests {
 		}
 
 		@Override
-		public Class<?> getObjectType() {
+		public @Nullable Class<?> getObjectType() {
 			return null;
 		}
 
@@ -1756,17 +1798,17 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties
 	public static class BasicProperties {
 
-		private String name;
+		private @Nullable String name;
 
-		private int[] array;
+		private int @Nullable [] array;
 
-		private List<Integer> list = new ArrayList<>();
+		private @Nullable List<Integer> list = new ArrayList<>();
 
-		private Duration duration;
+		private @Nullable Duration duration;
 
 		// No getter - you should be able to bind to a write-only bean
 
-		public void setName(String name) {
+		public void setName(@Nullable String name) {
 			// Must be public for XML
 			this.name = name;
 		}
@@ -1775,23 +1817,23 @@ class ConfigurationPropertiesTests {
 			this.array = values;
 		}
 
-		int[] getArray() {
+		int @Nullable [] getArray() {
 			return this.array;
 		}
 
-		List<Integer> getList() {
+		@Nullable List<Integer> getList() {
 			return this.list;
 		}
 
-		void setList(List<Integer> list) {
+		void setList(@Nullable List<Integer> list) {
 			this.list = list;
 		}
 
-		Duration getDuration() {
+		@Nullable Duration getDuration() {
 			return this.duration;
 		}
 
-		void setDuration(Duration duration) {
+		void setDuration(@Nullable Duration duration) {
 			this.duration = duration;
 		}
 
@@ -1800,11 +1842,11 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties
 	static class NestedProperties {
 
-		private String name;
+		private @Nullable String name;
 
 		private final Nested nested = new Nested();
 
-		void setName(String name) {
+		void setName(@Nullable String name) {
 			this.name = name;
 		}
 
@@ -1814,9 +1856,9 @@ class ConfigurationPropertiesTests {
 
 		static class Nested {
 
-			private String name;
+			private @Nullable String name;
 
-			void setName(String name) {
+			void setName(@Nullable String name) {
 				this.name = name;
 			}
 
@@ -1863,6 +1905,7 @@ class ConfigurationPropertiesTests {
 	static class Jsr303Properties extends BasicProperties {
 
 		@NotEmpty
+		@SuppressWarnings("NullAway.Init")
 		private String description;
 
 		String getDescription() {
@@ -1920,9 +1963,9 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties
 	static class WithoutAnnotationValueProperties {
 
-		private String name;
+		private @Nullable String name;
 
-		void setName(String name) {
+		void setName(@Nullable String name) {
 			this.name = name;
 		}
 
@@ -1934,13 +1977,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties
 	static class MapProperties {
 
-		private Map<String, String> mymap;
+		private @Nullable Map<String, String> mymap;
 
-		void setMymap(Map<String, String> mymap) {
+		void setMymap(@Nullable Map<String, String> mymap) {
 			this.mymap = mymap;
 		}
 
-		Map<String, String> getMymap() {
+		@Nullable Map<String, String> getMymap() {
 			return this.mymap;
 		}
 
@@ -1957,7 +2000,7 @@ class ConfigurationPropertiesTests {
 			assertThat(this.properties).isNotNull();
 		}
 
-		String getName() {
+		@Nullable String getName() {
 			return this.properties.name;
 		}
 
@@ -1974,6 +2017,7 @@ class ConfigurationPropertiesTests {
 	static class ValidatedImplementationProperties implements InterfaceForValidatedImplementation {
 
 		@NotNull
+		@SuppressWarnings("NullAway.Init")
 		private String foo;
 
 		@Override
@@ -1992,13 +2036,13 @@ class ConfigurationPropertiesTests {
 	static class WithPropertyPlaceholderValueProperties {
 
 		@Value("${default.value}")
-		private String value;
+		private @Nullable String value;
 
-		void setValue(String value) {
+		void setValue(@Nullable String value) {
 			this.value = value;
 		}
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
@@ -2008,23 +2052,23 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class WithEnumProperties {
 
-		private FooEnum theValue;
+		private @Nullable FooEnum theValue;
 
-		private List<FooEnum> theValues;
+		private @Nullable List<FooEnum> theValues;
 
-		void setTheValue(FooEnum value) {
+		void setTheValue(@Nullable FooEnum value) {
 			this.theValue = value;
 		}
 
-		FooEnum getTheValue() {
+		@Nullable FooEnum getTheValue() {
 			return this.theValue;
 		}
 
-		List<FooEnum> getTheValues() {
+		@Nullable List<FooEnum> getTheValues() {
 			return this.theValues;
 		}
 
-		void setTheValues(List<FooEnum> theValues) {
+		void setTheValues(@Nullable List<FooEnum> theValues) {
 			this.theValues = theValues;
 		}
 
@@ -2040,13 +2084,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties(prefix = "test", ignoreUnknownFields = false)
 	static class WithCharArrayProperties {
 
-		private char[] chars;
+		private char @Nullable [] chars;
 
-		char[] getChars() {
+		char @Nullable [] getChars() {
 			return this.chars;
 		}
 
-		void setChars(char[] chars) {
+		void setChars(char @Nullable [] chars) {
 			this.chars = chars;
 		}
 
@@ -2056,23 +2100,23 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class WithRelaxedNamesProperties {
 
-		private String fooBar;
+		private @Nullable String fooBar;
 
-		private String barBAZ;
+		private @Nullable String barBAZ;
 
-		String getFooBar() {
+		@Nullable String getFooBar() {
 			return this.fooBar;
 		}
 
-		void setFooBar(String fooBar) {
+		void setFooBar(@Nullable String fooBar) {
 			this.fooBar = fooBar;
 		}
 
-		String getBarBAZ() {
+		@Nullable String getBarBAZ() {
 			return this.barBAZ;
 		}
 
-		void setBarBAZ(String barBAZ) {
+		void setBarBAZ(@Nullable String barBAZ) {
 			this.barBAZ = barBAZ;
 		}
 
@@ -2083,13 +2127,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class WithMapProperties {
 
-		private Map<String, String> map;
+		private @Nullable Map<String, String> map;
 
-		Map<String, String> getMap() {
+		@Nullable Map<String, String> getMap() {
 			return this.map;
 		}
 
-		void setMap(Map<String, String> map) {
+		void setMap(@Nullable Map<String, String> map) {
 			this.map = map;
 		}
 
@@ -2099,13 +2143,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class WithComplexMapProperties {
 
-		private Map<String, Map<String, String>> map;
+		private @Nullable Map<String, Map<String, String>> map;
 
-		Map<String, Map<String, String>> getMap() {
+		@Nullable Map<String, Map<String, String>> getMap() {
 			return this.map;
 		}
 
-		void setMap(Map<String, Map<String, String>> map) {
+		void setMap(@Nullable Map<String, Map<String, String>> map) {
 			this.map = map;
 		}
 
@@ -2115,13 +2159,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class WithIntegerMapProperties {
 
-		private Map<String, Map<Integer, Foo>> map;
+		private @Nullable Map<String, Map<Integer, Foo>> map;
 
-		Map<String, Map<Integer, Foo>> getMap() {
+		@Nullable Map<String, Map<Integer, Foo>> getMap() {
 			return this.map;
 		}
 
-		void setMap(Map<String, Map<Integer, Foo>> map) {
+		void setMap(@Nullable Map<String, Map<Integer, Foo>> map) {
 			this.map = map;
 		}
 
@@ -2133,13 +2177,13 @@ class ConfigurationPropertiesTests {
 
 		private int foo;
 
-		private String bar;
+		private @Nullable String bar;
 
-		String getBar() {
+		@Nullable String getBar() {
 			return this.bar;
 		}
 
-		void setBar(String bar) {
+		void setBar(@Nullable String bar) {
 			this.bar = bar;
 		}
 
@@ -2157,13 +2201,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class PersonProperties {
 
-		private Person person;
+		private @Nullable Person person;
 
-		Person getPerson() {
+		@Nullable Person getPerson() {
 			return this.person;
 		}
 
-		void setPerson(Person person) {
+		void setPerson(@Nullable Person person) {
 			this.person = person;
 		}
 
@@ -2173,23 +2217,23 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class PersonAndAlienProperties {
 
-		private Person person;
+		private @Nullable Person person;
 
-		private Alien alien;
+		private @Nullable Alien alien;
 
-		Person getPerson() {
+		@Nullable Person getPerson() {
 			return this.person;
 		}
 
-		void setPerson(Person person) {
+		void setPerson(@Nullable Person person) {
 			this.person = person;
 		}
 
-		Alien getAlien() {
+		@Nullable Alien getAlien() {
 			return this.alien;
 		}
 
-		void setAlien(Alien alien) {
+		void setAlien(@Nullable Alien alien) {
 			this.alien = alien;
 		}
 
@@ -2199,23 +2243,23 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class PersonAndAliensProperties {
 
-		private Person person;
+		private @Nullable Person person;
 
-		private List<Alien> aliens;
+		private @Nullable List<Alien> aliens;
 
-		Person getPerson() {
+		@Nullable Person getPerson() {
 			return this.person;
 		}
 
-		void setPerson(Person person) {
+		void setPerson(@Nullable Person person) {
 			this.person = person;
 		}
 
-		List<Alien> getAliens() {
+		@Nullable List<Alien> getAliens() {
 			return this.aliens;
 		}
 
-		void setAliens(List<Alien> aliens) {
+		void setAliens(@Nullable List<Alien> aliens) {
 			this.aliens = aliens;
 		}
 
@@ -2237,7 +2281,7 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties
 	static class ValidatorProperties implements Validator {
 
-		private String foo;
+		private @Nullable String foo;
 
 		@Override
 		public boolean supports(Class<?> type) {
@@ -2249,11 +2293,11 @@ class ConfigurationPropertiesTests {
 			ValidationUtils.rejectIfEmpty(errors, "foo", "TEST1");
 		}
 
-		String getFoo() {
+		@Nullable String getFoo() {
 			return this.foo;
 		}
 
-		void setFoo(String foo) {
+		void setFoo(@Nullable String foo) {
 			this.foo = foo;
 		}
 
@@ -2293,9 +2337,9 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class WithSetterThatThrowsValidationExceptionProperties {
 
-		private String foo;
+		private @Nullable String foo;
 
-		String getFoo() {
+		@Nullable String getFoo() {
 			return this.foo;
 		}
 
@@ -2311,13 +2355,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("custom")
 	static class WithCustomValidatorProperties {
 
-		private String foo;
+		private @Nullable String foo;
 
-		String getFoo() {
+		@Nullable String getFoo() {
 			return this.foo;
 		}
 
-		void setFoo(String foo) {
+		void setFoo(@Nullable String foo) {
 			this.foo = foo;
 		}
 
@@ -2327,13 +2371,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class ListOfGenericClassProperties {
 
-		private List<Class<? extends Throwable>> list;
+		private @Nullable List<Class<? extends Throwable>> list;
 
-		List<Class<? extends Throwable>> getList() {
+		@Nullable List<Class<? extends Throwable>> getList() {
 			return this.list;
 		}
 
-		void setList(List<Class<? extends Throwable>> list) {
+		void setList(@Nullable List<Class<? extends Throwable>> list) {
 			this.list = list;
 		}
 
@@ -2343,13 +2387,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class FileProperties {
 
-		private File file;
+		private @Nullable File file;
 
-		File getFile() {
+		@Nullable File getFile() {
 			return this.file;
 		}
 
-		void setFile(File file) {
+		void setFile(@Nullable File file) {
 			this.file = file;
 		}
 
@@ -2359,24 +2403,24 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class DataSizeProperties {
 
-		private DataSize size;
+		private @Nullable DataSize size;
 
 		@DataSizeUnit(DataUnit.KILOBYTES)
-		private DataSize anotherSize;
+		private @Nullable DataSize anotherSize;
 
-		DataSize getSize() {
+		@Nullable DataSize getSize() {
 			return this.size;
 		}
 
-		void setSize(DataSize size) {
+		void setSize(@Nullable DataSize size) {
 			this.size = size;
 		}
 
-		DataSize getAnotherSize() {
+		@Nullable DataSize getAnotherSize() {
 			return this.anotherSize;
 		}
 
-		void setAnotherSize(DataSize anotherSize) {
+		void setAnotherSize(@Nullable DataSize anotherSize) {
 			this.anotherSize = anotherSize;
 		}
 
@@ -2385,7 +2429,7 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class OtherInjectedProperties {
 
-		final DataSizeProperties dataSizeProperties;
+		final @Nullable DataSizeProperties dataSizeProperties;
 
 		OtherInjectedProperties(ObjectProvider<DataSizeProperties> dataSizeProperties) {
 			this.dataSizeProperties = dataSizeProperties.getIfUnique();
@@ -2578,6 +2622,7 @@ class ConfigurationPropertiesTests {
 		@Override
 		public Person convert(String source) {
 			String[] content = StringUtils.split(source, " ");
+			assertThat(content).isNotNull();
 			return new Person(content[0], content[1]);
 		}
 
@@ -2600,8 +2645,9 @@ class ConfigurationPropertiesTests {
 		}
 
 		@Override
-		public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+		public Object convert(@Nullable Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
 			String[] content = StringUtils.split((String) source, " ");
+			assertThat(content).isNotNull();
 			return new Person(content[0], content[1]);
 		}
 
@@ -2669,15 +2715,15 @@ class ConfigurationPropertiesTests {
 
 	static class Foo {
 
-		private String a;
+		private @Nullable String a;
 
 		private int b;
 
-		String getA() {
+		@Nullable String getA() {
 			return this.a;
 		}
 
-		void setA(String a) {
+		void setA(@Nullable String a) {
 			this.a = a;
 		}
 
@@ -2796,13 +2842,13 @@ class ConfigurationPropertiesTests {
 
 		static class Nested {
 
-			private Outer outer;
+			private @Nullable Outer outer;
 
-			Outer getOuter() {
+			@Nullable Outer getOuter() {
 				return this.outer;
 			}
 
-			void setOuter(Outer nested) {
+			void setOuter(@Nullable Outer nested) {
 				this.outer = nested;
 			}
 
@@ -2890,13 +2936,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class JavaBeanNestedConstructorBindingProperties {
 
-		private Nested nested;
+		private @Nullable Nested nested;
 
-		Nested getNested() {
+		@Nullable Nested getNested() {
 			return this.nested;
 		}
 
-		void setNested(Nested nested) {
+		void setNested(@Nullable Nested nested) {
 			this.nested = nested;
 		}
 
@@ -2926,13 +2972,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class JavaBeanNonDefaultConstructorProperties {
 
-		private Nested nested;
+		private @Nullable Nested nested;
 
-		Nested getNested() {
+		@Nullable Nested getNested() {
 			return this.nested;
 		}
 
-		void setNested(Nested nested) {
+		void setNested(@Nullable Nested nested) {
 			this.nested = nested;
 		}
 
@@ -3076,13 +3122,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class WithCustomConverterAndObjectToObjectMethodProperties {
 
-		private WithPublicObjectToObjectMethod item;
+		private @Nullable WithPublicObjectToObjectMethod item;
 
-		WithPublicObjectToObjectMethod getItem() {
+		@Nullable WithPublicObjectToObjectMethod getItem() {
 			return this.item;
 		}
 
-		void setItem(WithPublicObjectToObjectMethod item) {
+		void setItem(@Nullable WithPublicObjectToObjectMethod item) {
 			this.item = item;
 		}
 
@@ -3199,17 +3245,17 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class PotentiallyConstructorBoundProperties {
 
-		private String prop;
+		private @Nullable String prop;
 
 		PotentiallyConstructorBoundProperties(String notAProperty) {
 
 		}
 
-		String getProp() {
+		@Nullable String getProp() {
 			return this.prop;
 		}
 
-		void setProp(String prop) {
+		void setProp(@Nullable String prop) {
 			this.prop = prop;
 		}
 
@@ -3223,13 +3269,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class ResourceArrayProperties {
 
-		private Resource[] resources;
+		private Resource @Nullable [] resources;
 
-		Resource[] getResources() {
+		Resource @Nullable [] getResources() {
 			return this.resources;
 		}
 
-		void setResources(Resource[] resources) {
+		void setResources(Resource @Nullable [] resources) {
 			this.resources = resources;
 		}
 
@@ -3243,13 +3289,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class ResourceCollectionProperties {
 
-		private Collection<Resource> resources;
+		private @Nullable Collection<Resource> resources;
 
-		Collection<Resource> getResources() {
+		@Nullable Collection<Resource> getResources() {
 			return this.resources;
 		}
 
-		void setResources(Collection<Resource> resources) {
+		void setResources(@Nullable Collection<Resource> resources) {
 			this.resources = resources;
 		}
 
@@ -3311,13 +3357,13 @@ class ConfigurationPropertiesTests {
 	@ConfigurationProperties("test")
 	static class SetterBoundCustomListProperties {
 
-		private CustomList<String> values;
+		private @Nullable CustomList<String> values;
 
-		CustomList<String> getValues() {
+		@Nullable CustomList<String> getValues() {
 			return this.values;
 		}
 
-		void setValues(CustomList<String> values) {
+		void setValues(@Nullable CustomList<String> values) {
 			this.values = values;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/ConversionServiceDeducerTests.java

@@ -70,6 +70,7 @@ class ConversionServiceDeducerTests {
 		applicationContext.getBeanFactory().setConversionService(conversionService);
 		ConversionServiceDeducer deducer = new ConversionServiceDeducer(applicationContext);
 		List<ConversionService> conversionServices = deducer.getConversionServices();
+		assertThat(conversionServices).isNotNull();
 		assertThat(conversionServices).containsOnly(conversionService);
 		assertThat(conversionServices.get(0)).isSameAs(conversionService);
 	}
@@ -106,6 +107,7 @@ class ConversionServiceDeducerTests {
 		ConversionServiceDeducer deducer = new ConversionServiceDeducer(applicationContext);
 		List<ConversionService> conversionServices = deducer.getConversionServices();
 		InputStream inputStream = new ByteArrayInputStream("test".getBytes(StandardCharsets.UTF_8));
+		assertThat(conversionServices).isNotNull();
 		assertThat(conversionServices.get(0).convert(inputStream, String.class)).isEqualTo("test");
 	}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/IncompatibleConfigurationFailureAnalyzerTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context.properties;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.diagnostics.FailureAnalysis;
@@ -32,13 +33,14 @@ class IncompatibleConfigurationFailureAnalyzerTests {
 	@Test
 	void incompatibleConfigurationListsKeys() {
 		FailureAnalysis failureAnalysis = performAnalysis("spring.first.key", "spring.second.key");
+		assertThat(failureAnalysis).isNotNull();
 		assertThat(failureAnalysis.getDescription()).contains(
 				"The following configuration properties have incompatible values: [spring.first.key, spring.second.key]");
 		assertThat(failureAnalysis.getAction())
 			.contains("Review the docs for spring.first.key, spring.second.key and change the configured values.");
 	}
 
-	private FailureAnalysis performAnalysis(String... keys) {
+	private @Nullable FailureAnalysis performAnalysis(String... keys) {
 		IncompatibleConfigurationException failure = new IncompatibleConfigurationException(keys);
 		return new IncompatibleConfigurationFailureAnalyzer().analyze(failure);
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/properties/MultiConstructorConfigurationProperties.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.context.properties;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Class used to test multi-constructor binding. Must be public and have public
  * constructors.
@@ -24,7 +26,7 @@ package org.springframework.boot.context.properties;
  */
 public class MultiConstructorConfigurationProperties {
 
-	private String name;
+	private @Nullable String name;
 
 	private int age;
 
@@ -35,11 +37,11 @@ public class MultiConstructorConfigurationProperties {
 		this.name = name;
 	}
 
-	public String getName() {
+	public @Nullable String getName() {
 		return this.name;
 	}
 
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/NotConstructorBoundInjectionFailureAnalyzerTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context.properties;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.beans.FatalBeanException;
@@ -42,6 +43,7 @@ class NotConstructorBoundInjectionFailureAnalyzerTests {
 	void failureAnalysisForConfigurationPropertiesThatShouldHaveBeenConstructorBound() {
 		FailureAnalysis analysis = analyzeFailure(
 				createFailure(ShouldHaveUsedConstructorBindingPropertiesConfiguration.class));
+		assertThat(analysis).isNotNull();
 		assertThat(analysis.getDescription()).isEqualTo(ConstructorBoundProperties.class.getSimpleName()
 				+ " is annotated with @" + ConstructorBinding.class.getSimpleName()
 				+ " but it is defined as a regular bean which caused dependency injection to fail.");
@@ -57,7 +59,7 @@ class NotConstructorBoundInjectionFailureAnalyzerTests {
 		assertThat(analysis).isNull();
 	}
 
-	private FatalBeanException createFailure(Class<?> config) {
+	private @Nullable FatalBeanException createFailure(Class<?> config) {
 		try (AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext()) {
 			context.register(config);
 			context.refresh();
@@ -68,7 +70,7 @@ class NotConstructorBoundInjectionFailureAnalyzerTests {
 		}
 	}
 
-	private FailureAnalysis analyzeFailure(Exception failure) {
+	private @Nullable FailureAnalysis analyzeFailure(@Nullable Exception failure) {
 		assertThat(failure).isNotNull();
 		FailureAnalysis analysis = this.analyzer.analyze(failure);
 		if (analysis != null) {
@@ -101,18 +103,18 @@ class NotConstructorBoundInjectionFailureAnalyzerTests {
 	@ConfigurationProperties("test")
 	static class JavaBeanBoundProperties {
 
-		private String name;
+		private @Nullable String name;
 
 		@Autowired
 		JavaBeanBoundProperties(String dependency) {
 
 		}
 
-		String getName() {
+		@Nullable String getName() {
 			return this.name;
 		}
 
-		void setName(String name) {
+		void setName(@Nullable String name) {
 			this.name = name;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/PropertyMapperTests.java

@@ -22,6 +22,7 @@ import java.util.function.Function;
 import java.util.function.Supplier;
 
 import org.assertj.core.api.Assertions;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
@@ -63,6 +64,7 @@ class PropertyMapperTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void fromWhenSupplierIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> this.map.from((Supplier<?>) null))
 			.withMessageContaining("'supplier' must not be null");
@@ -80,6 +82,7 @@ class PropertyMapperTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void toWhenConsumerIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> this.map.from(() -> "").to(null))
 			.withMessageContaining("'consumer' must not be null");
@@ -100,6 +103,7 @@ class PropertyMapperTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void asWhenAdapterIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> this.map.from(() -> "").as(null))
 			.withMessageContaining("'adapter' must not be null");
@@ -262,7 +266,10 @@ class PropertyMapperTests {
 
 		@Test
 		void asWhenNull() {
-			String value = this.map.from((String) null).always().as(String::valueOf).toInstance((string) -> string);
+			String value = this.map.from((String) null).always().as(String::valueOf).toInstance((string) -> {
+				assertThat(string).isNotNull();
+				return string;
+			});
 			assertThat(value).isEqualTo("null");
 		}
 
@@ -336,16 +343,16 @@ class PropertyMapperTests {
 
 	static class ExampleDest {
 
-		private String name;
+		private @Nullable String name;
 
 		boolean setNameCalled;
 
-		void setName(String name) {
+		void setName(@Nullable String name) {
 			this.name = name;
 			this.setNameCalled = true;
 		}
 
-		String getName() {
+		@Nullable String getName() {
 			return this.name;
 		}
 
@@ -355,21 +362,21 @@ class PropertyMapperTests {
 
 		private final String name;
 
-		private final Integer age;
+		private final @Nullable Integer age;
 
 		final boolean withAgeCalled;
 
-		Immutable(String name, Integer age) {
+		Immutable(String name, @Nullable Integer age) {
 			this(name, age, false);
 		}
 
-		private Immutable(String name, Integer age, boolean withAgeCalled) {
+		private Immutable(String name, @Nullable Integer age, boolean withAgeCalled) {
 			this.name = name;
 			this.age = age;
 			this.withAgeCalled = withAgeCalled;
 		}
 
-		Immutable withAge(Integer age) {
+		Immutable withAge(@Nullable Integer age) {
 			return new Immutable(this.name, age, true);
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/WithPublicStringConstructorProperties.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.context.properties;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * A {@link ConfigurationProperties @ConfigurationProperties} with an additional
  * single-arg public constructor. Used in {@link ConfigurationPropertiesTests}.
@@ -25,7 +27,7 @@ package org.springframework.boot.context.properties;
 @ConfigurationProperties("test")
 public class WithPublicStringConstructorProperties {
 
-	private String a;
+	private @Nullable String a;
 
 	public WithPublicStringConstructorProperties() {
 	}
@@ -34,11 +36,11 @@ public class WithPublicStringConstructorProperties {
 		this.a = a;
 	}
 
-	public String getA() {
+	public @Nullable String getA() {
 		return this.a;
 	}
 
-	public void setA(String a) {
+	public void setA(@Nullable String a) {
 		this.a = a;
 	}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/ArrayBinderTests.java

@@ -142,7 +142,9 @@ class ArrayBinderTests {
 		this.sources.add(source);
 		assertThatExceptionOfType(BindException.class).isThrownBy(() -> this.binder.bind("foo", INTEGER_ARRAY))
 			.satisfies((ex) -> {
-				Set<ConfigurationProperty> unbound = ((UnboundConfigurationPropertiesException) ex.getCause())
+				Throwable cause = ex.getCause();
+				assertThat(cause).isNotNull();
+				Set<ConfigurationProperty> unbound = ((UnboundConfigurationPropertiesException) cause)
 					.getUnboundProperties();
 				assertThat(unbound).hasSize(1);
 				ConfigurationProperty property = unbound.iterator().next();

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/BackCompatibilityBinderIntegrationTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.context.properties.bind;
 
 import java.util.Collections;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.env.StandardEnvironment;
@@ -60,13 +61,13 @@ class BackCompatibilityBinderIntegrationTests {
 
 	static class ExampleCamelCaseBean {
 
-		private String zkNodes;
+		private @Nullable String zkNodes;
 
-		String getZkNodes() {
+		@Nullable String getZkNodes() {
 			return this.zkNodes;
 		}
 
-		void setZkNodes(String zkNodes) {
+		void setZkNodes(@Nullable String zkNodes) {
 			this.zkNodes = zkNodes;
 		}
 
@@ -74,13 +75,13 @@ class BackCompatibilityBinderIntegrationTests {
 
 	static class PasswordProperties {
 
-		private String password;
+		private @Nullable String password;
 
-		String getPassword() {
+		@Nullable String getPassword() {
 			return this.password;
 		}
 
-		void setPassword(String password) {
+		void setPassword(@Nullable String password) {
 			this.password = password;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/BindConverterTests.java

@@ -24,6 +24,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.function.Consumer;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.ExtendWith;
 import org.mockito.Mock;
@@ -53,6 +54,7 @@ import static org.mockito.BDDMockito.then;
 class BindConverterTests {
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Consumer<PropertyEditorRegistry> propertyEditorInitializer;
 
 	@Test
@@ -121,6 +123,7 @@ class BindConverterTests {
 	void convertWhenHasCustomEditorShouldConvert() {
 		BindConverter bindConverter = getPropertyEditorOnlyBindConverter(this::registerSampleTypeEditor);
 		SampleType converted = bindConverter.convert("test", ResolvableType.forClass(SampleType.class));
+		assertThat(converted).isNotNull();
 		assertThat(converted.getText()).isEqualTo("test");
 	}
 
@@ -128,6 +131,7 @@ class BindConverterTests {
 	void convertWhenHasEditorByConventionShouldConvert() {
 		BindConverter bindConverter = getPropertyEditorOnlyBindConverter(null);
 		ConventionType converted = bindConverter.convert("test", ResolvableType.forClass(ConventionType.class));
+		assertThat(converted).isNotNull();
 		assertThat(converted.getText()).isEqualTo("test");
 	}
 
@@ -144,6 +148,7 @@ class BindConverterTests {
 	void convertWhenHasEditorForArrayElementShouldConvert() {
 		BindConverter bindConverter = getPropertyEditorOnlyBindConverter(this::registerSampleTypeEditor);
 		SampleType[] converted = bindConverter.convert("test", ResolvableType.forClass(SampleType[].class));
+		assertThat(converted).isNotNull();
 		assertThat(converted).isNotEmpty();
 		assertThat(converted[0].getText()).isEqualTo("test");
 	}
@@ -152,6 +157,7 @@ class BindConverterTests {
 	void convertWhenConversionServiceCanConvertShouldConvert() {
 		BindConverter bindConverter = getBindConverter(new SampleTypeConverter());
 		SampleType converted = bindConverter.convert("test", ResolvableType.forClass(SampleType.class));
+		assertThat(converted).isNotNull();
 		assertThat(converted.getText()).isEqualTo("test");
 	}
 
@@ -169,6 +175,7 @@ class BindConverterTests {
 		BindConverter bindConverter = BindConverter.get(Collections.singletonList(new GenericConversionService()),
 				null);
 		File result = bindConverter.convert(".", ResolvableType.forClass(File.class));
+		assertThat(result).isNotNull();
 		assertThat(result.getPath()).isEqualTo(".");
 	}
 
@@ -177,6 +184,7 @@ class BindConverterTests {
 		BindConverter bindConverter = BindConverter.get(Collections.singletonList(new GenericConversionService()),
 				null);
 		Duration result = bindConverter.convert("10s", ResolvableType.forClass(Duration.class));
+		assertThat(result).isNotNull();
 		assertThat(result.getSeconds()).isEqualTo(10);
 	}
 
@@ -215,7 +223,7 @@ class BindConverterTests {
 	}
 
 	private BindConverter getPropertyEditorOnlyBindConverter(
-			Consumer<PropertyEditorRegistry> propertyEditorInitializer) {
+			@Nullable Consumer<PropertyEditorRegistry> propertyEditorInitializer) {
 		return BindConverter.get(Collections.singletonList(new ThrowingConversionService()), propertyEditorInitializer);
 	}
 
@@ -231,9 +239,9 @@ class BindConverterTests {
 
 	static class SampleType {
 
-		private String text;
+		private @Nullable String text;
 
-		String getText() {
+		@Nullable String getText() {
 			return this.text;
 		}
 
@@ -266,9 +274,9 @@ class BindConverterTests {
 
 	static class ConventionType {
 
-		private String text;
+		private @Nullable String text;
 
-		String getText() {
+		@Nullable String getText() {
 			return this.text;
 		}
 
@@ -291,22 +299,22 @@ class BindConverterTests {
 	static class ThrowingConversionService implements ConversionService {
 
 		@Override
-		public boolean canConvert(Class<?> sourceType, Class<?> targetType) {
+		public boolean canConvert(@Nullable Class<?> sourceType, Class<?> targetType) {
 			throw new AssertionError("Should not call conversion service");
 		}
 
 		@Override
-		public boolean canConvert(TypeDescriptor sourceType, TypeDescriptor targetType) {
+		public boolean canConvert(@Nullable TypeDescriptor sourceType, TypeDescriptor targetType) {
 			throw new AssertionError("Should not call conversion service");
 		}
 
 		@Override
-		public <T> T convert(Object source, Class<T> targetType) {
+		public <T> T convert(@Nullable Object source, Class<T> targetType) {
 			throw new AssertionError("Should not call conversion service");
 		}
 
 		@Override
-		public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
+		public Object convert(@Nullable Object source, @Nullable TypeDescriptor sourceType, TypeDescriptor targetType) {
 			throw new AssertionError("Should not call conversion service");
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/BindResultTests.java

@@ -44,12 +44,15 @@ import static org.mockito.BDDMockito.then;
 class BindResultTests {
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Consumer<String> consumer;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Function<String, String> mapper;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Supplier<String> supplier;
 
 	@Test
@@ -78,6 +81,7 @@ class BindResultTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void ifBoundWhenConsumerIsNullShouldThrowException() {
 		BindResult<String> result = BindResult.of("foo");
 		assertThatIllegalArgumentException().isThrownBy(() -> result.ifBound(null))
@@ -99,6 +103,7 @@ class BindResultTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void mapWhenMapperIsNullShouldThrowException() {
 		BindResult<String> result = BindResult.of("foo");
 		assertThatIllegalArgumentException().isThrownBy(() -> result.map(null))

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/BindableRuntimeHintsRegistrarTests.java

@@ -25,6 +25,7 @@ import java.util.Map;
 import java.util.function.Consumer;
 
 import org.apache.tomcat.jdbc.pool.PoolProperties;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.aot.hint.ExecutableHint;
@@ -295,7 +296,7 @@ class BindableRuntimeHintsRegistrarTests {
 			throws NoSuchMethodException, SecurityException {
 		Constructor<?> constructor = PoolProperties.InterceptorProperty.class.getConstructor(String.class,
 				String.class);
-		String[] parameterNames = new StandardReflectionParameterNameDiscoverer().getParameterNames(constructor);
+		@Nullable String[] parameterNames = new StandardReflectionParameterNameDiscoverer().getParameterNames(constructor);
 		assertThat(parameterNames).isNull();
 		assertThatNoException().isThrownBy(() -> registerHints(PoolProperties.class));
 	}
@@ -425,24 +426,24 @@ class BindableRuntimeHintsRegistrarTests {
 
 	public static class WithExternalNested {
 
-		private String name;
+		private @Nullable String name;
 
 		@NestedConfigurationProperty
-		private SampleType sampleType;
+		private @Nullable SampleType sampleType;
 
-		public String getName() {
+		public @Nullable String getName() {
 			return this.name;
 		}
 
-		public void setName(String name) {
+		public void setName(@Nullable String name) {
 			this.name = name;
 		}
 
-		public SampleType getSampleType() {
+		public @Nullable SampleType getSampleType() {
 			return this.sampleType;
 		}
 
-		public void setSampleType(SampleType sampleType) {
+		public void setSampleType(@Nullable SampleType sampleType) {
 			this.sampleType = sampleType;
 		}
 
@@ -451,13 +452,13 @@ class BindableRuntimeHintsRegistrarTests {
 	public static class WithRecursive {
 
 		@NestedConfigurationProperty
-		private Recursive recursive;
+		private @Nullable Recursive recursive;
 
-		public Recursive getRecursive() {
+		public @Nullable Recursive getRecursive() {
 			return this.recursive;
 		}
 
-		public void setRecursive(Recursive recursive) {
+		public void setRecursive(@Nullable Recursive recursive) {
 			this.recursive = recursive;
 		}
 
@@ -466,9 +467,9 @@ class BindableRuntimeHintsRegistrarTests {
 	public static class ImmutableWithRecursive {
 
 		@NestedConfigurationProperty
-		private final ImmutableRecursive recursive;
+		private final @Nullable ImmutableRecursive recursive;
 
-		ImmutableWithRecursive(ImmutableRecursive recursive) {
+		ImmutableWithRecursive(@Nullable ImmutableRecursive recursive) {
 			this.recursive = recursive;
 		}
 
@@ -476,8 +477,10 @@ class BindableRuntimeHintsRegistrarTests {
 
 	public static class WithWellKnownTypes implements ApplicationContextAware, EnvironmentAware {
 
+		@SuppressWarnings("NullAway.Init")
 		private ApplicationContext applicationContext;
 
+		@SuppressWarnings("NullAway.Init")
 		private Environment environment;
 
 		public ApplicationContext getApplicationContext() {
@@ -516,23 +519,23 @@ class BindableRuntimeHintsRegistrarTests {
 
 	public static class PackagePrivateGettersAndSetters {
 
-		private String alpha;
+		private @Nullable String alpha;
 
-		private Map<String, String> bravo;
+		private @Nullable Map<String, String> bravo;
 
-		String getAlpha() {
+		@Nullable String getAlpha() {
 			return this.alpha;
 		}
 
-		void setAlpha(String alpha) {
+		void setAlpha(@Nullable String alpha) {
 			this.alpha = alpha;
 		}
 
-		Map<String, String> getBravo() {
+		@Nullable Map<String, String> getBravo() {
 			return this.bravo;
 		}
 
-		void setBravo(Map<String, String> bravo) {
+		void setBravo(@Nullable Map<String, String> bravo) {
 			this.bravo = bravo;
 		}
 
@@ -563,13 +566,13 @@ class BindableRuntimeHintsRegistrarTests {
 
 	public static class Recursive {
 
-		private Recursive recursive;
+		private @Nullable Recursive recursive;
 
-		public Recursive getRecursive() {
+		public @Nullable Recursive getRecursive() {
 			return this.recursive;
 		}
 
-		public void setRecursive(Recursive recursive) {
+		public void setRecursive(@Nullable Recursive recursive) {
 			this.recursive = recursive;
 		}
 
@@ -578,9 +581,9 @@ class BindableRuntimeHintsRegistrarTests {
 	public static class ImmutableRecursive {
 
 		@SuppressWarnings("unused")
-		private final ImmutableRecursive recursive;
+		private final @Nullable ImmutableRecursive recursive;
 
-		ImmutableRecursive(ImmutableRecursive recursive) {
+		ImmutableRecursive(@Nullable ImmutableRecursive recursive) {
 			this.recursive = recursive;
 		}
 
@@ -589,13 +592,13 @@ class BindableRuntimeHintsRegistrarTests {
 	public static class WithCrossReference {
 
 		@NestedConfigurationProperty
-		private CrossReferenceA crossReferenceA;
+		private @Nullable CrossReferenceA crossReferenceA;
 
-		public void setCrossReferenceA(CrossReferenceA crossReferenceA) {
+		public void setCrossReferenceA(@Nullable CrossReferenceA crossReferenceA) {
 			this.crossReferenceA = crossReferenceA;
 		}
 
-		public CrossReferenceA getCrossReferenceA() {
+		public @Nullable CrossReferenceA getCrossReferenceA() {
 			return this.crossReferenceA;
 		}
 
@@ -604,13 +607,13 @@ class BindableRuntimeHintsRegistrarTests {
 	public static class CrossReferenceA {
 
 		@NestedConfigurationProperty
-		private CrossReferenceB crossReferenceB;
+		private @Nullable CrossReferenceB crossReferenceB;
 
-		public void setCrossReferenceB(CrossReferenceB crossReferenceB) {
+		public void setCrossReferenceB(@Nullable CrossReferenceB crossReferenceB) {
 			this.crossReferenceB = crossReferenceB;
 		}
 
-		public CrossReferenceB getCrossReferenceB() {
+		public @Nullable CrossReferenceB getCrossReferenceB() {
 			return this.crossReferenceB;
 		}
 
@@ -618,13 +621,13 @@ class BindableRuntimeHintsRegistrarTests {
 
 	public static class CrossReferenceB {
 
-		private CrossReferenceA crossReferenceA;
+		private @Nullable CrossReferenceA crossReferenceA;
 
-		public void setCrossReferenceA(CrossReferenceA crossReferenceA) {
+		public void setCrossReferenceA(@Nullable CrossReferenceA crossReferenceA) {
 			this.crossReferenceA = crossReferenceA;
 		}
 
-		public CrossReferenceA getCrossReferenceA() {
+		public @Nullable CrossReferenceA getCrossReferenceA() {
 			return this.crossReferenceA;
 		}
 
@@ -633,9 +636,9 @@ class BindableRuntimeHintsRegistrarTests {
 	public static class WithGeneric {
 
 		@NestedConfigurationProperty
-		private GenericObject<?> generic;
+		private @Nullable GenericObject<?> generic;
 
-		public GenericObject<?> getGeneric() {
+		public @Nullable GenericObject<?> getGeneric() {
 			return this.generic;
 		}
 
@@ -665,13 +668,13 @@ class BindableRuntimeHintsRegistrarTests {
 
 		public static class Nested {
 
-			private String field;
+			private @Nullable String field;
 
-			public String getField() {
+			public @Nullable String getField() {
 				return this.field;
 			}
 
-			public void setField(String field) {
+			public void setField(@Nullable String field) {
 				this.field = field;
 			}
 
@@ -697,13 +700,13 @@ class BindableRuntimeHintsRegistrarTests {
 
 			public static class Nested {
 
-				private String field;
+				private @Nullable String field;
 
-				public String getField() {
+				public @Nullable String getField() {
 					return this.field;
 				}
 
-				public void setField(String field) {
+				public void setField(@Nullable String field) {
 					this.field = field;
 				}
 
@@ -715,25 +718,25 @@ class BindableRuntimeHintsRegistrarTests {
 
 	public abstract static class BaseProperties {
 
-		private InheritedNested inheritedNested;
+		private @Nullable InheritedNested inheritedNested;
 
-		public InheritedNested getInheritedNested() {
+		public @Nullable InheritedNested getInheritedNested() {
 			return this.inheritedNested;
 		}
 
-		public void setInheritedNested(InheritedNested inheritedNested) {
+		public void setInheritedNested(@Nullable InheritedNested inheritedNested) {
 			this.inheritedNested = inheritedNested;
 		}
 
 		public static class InheritedNested {
 
-			private String alpha;
+			private @Nullable String alpha;
 
-			public String getAlpha() {
+			public @Nullable String getAlpha() {
 				return this.alpha;
 			}
 
-			public void setAlpha(String alpha) {
+			public void setAlpha(@Nullable String alpha) {
 				this.alpha = alpha;
 			}
 
@@ -743,13 +746,13 @@ class BindableRuntimeHintsRegistrarTests {
 
 	public static class ExtendingProperties extends BaseProperties {
 
-		private String bravo;
+		private @Nullable String bravo;
 
-		public String getBravo() {
+		public @Nullable String getBravo() {
 			return this.bravo;
 		}
 
-		public void setBravo(String bravo) {
+		public void setBravo(@Nullable String bravo) {
 			this.bravo = bravo;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/BindableTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.context.properties.bind;
 import java.lang.annotation.Annotation;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
+import java.util.function.Supplier;
 
 import org.junit.jupiter.api.Test;
 
@@ -41,12 +42,14 @@ import static org.mockito.Mockito.mock;
 class BindableTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void ofClassWhenTypeIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> Bindable.of((Class<?>) null))
 			.withMessageContaining("'type' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void ofTypeWhenTypeIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> Bindable.of((ResolvableType) null))
 			.withMessageContaining("'type' must not be null");
@@ -68,18 +71,23 @@ class BindableTests {
 		String instance = "foo";
 		ResolvableType type = ResolvableType.forClass(String.class);
 		assertThat(Bindable.ofInstance(instance).getType()).isEqualTo(type);
-		assertThat(Bindable.ofInstance(instance).getValue().get()).isEqualTo("foo");
+		Supplier<String> value = Bindable.ofInstance(instance).getValue();
+		assertThat(value).isNotNull();
+		assertThat(value.get()).isEqualTo("foo");
 	}
 
 	@Test
 	void ofClassWithExistingValueShouldSetTypeAndExistingValue() {
-		assertThat(Bindable.of(String.class).withExistingValue("foo").getValue().get()).isEqualTo("foo");
+		Supplier<String> value = Bindable.of(String.class).withExistingValue("foo").getValue();
+		assertThat(value).isNotNull();
+		assertThat(value.get()).isEqualTo("foo");
 	}
 
 	@Test
 	void ofTypeWithExistingValueShouldSetTypeAndExistingValue() {
-		assertThat(Bindable.of(ResolvableType.forClass(String.class)).withExistingValue("foo").getValue().get())
-			.isEqualTo("foo");
+		Supplier<Object> value = Bindable.of(ResolvableType.forClass(String.class)).withExistingValue("foo").getValue();
+		assertThat(value).isNotNull();
+		assertThat(value.get()).isEqualTo("foo");
 	}
 
 	@Test
@@ -93,7 +101,9 @@ class BindableTests {
 	void ofTypeWhenPrimitiveWithExistingValueWrapperShouldNotThrowException() {
 		Bindable<Integer> bindable = Bindable.<Integer>of(ResolvableType.forClass(int.class)).withExistingValue(123);
 		assertThat(bindable.getType().resolve()).isEqualTo(int.class);
-		assertThat(bindable.getValue().get()).isEqualTo(123);
+		Supplier<Integer> value = bindable.getValue();
+		assertThat(value).isNotNull();
+		assertThat(value.get()).isEqualTo(123);
 	}
 
 	@Test

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/BinderTests.java

@@ -25,6 +25,7 @@ import java.util.List;
 import java.util.Map;
 
 import jakarta.validation.Validation;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
 import org.mockito.invocation.InvocationOnMock;
@@ -71,12 +72,14 @@ class BinderTests {
 	private Binder binder = new Binder(this.sources);
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenSourcesIsNullArrayShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new Binder((ConfigurationPropertySource[]) null))
 			.withMessageContaining("'sources' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenSourcesIsNullIterableShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new Binder((Iterable<ConfigurationPropertySource>) null))
 			.withMessageContaining("'sources' must not be null");
@@ -95,6 +98,7 @@ class BinderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void bindWhenNameIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.binder.bind((ConfigurationPropertyName) null, Bindable.of(String.class),
@@ -103,6 +107,7 @@ class BinderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void bindWhenTargetIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.binder.bind(ConfigurationPropertyName.of("foo"), null, BindHandler.DEFAULT))
@@ -268,7 +273,7 @@ class BinderTests {
 		ConfigurationPropertySources.from(new PropertySource<String>("test") {
 
 			@Override
-			public Object getProperty(String name) {
+			public @Nullable Object getProperty(String name) {
 				return null;
 			}
 
@@ -301,7 +306,7 @@ class BinderTests {
 		Map<String, Object> source = new HashMap<>();
 		source.put("value", "hello");
 		source.put("", "bar");
-		Iterable<ConfigurationPropertySource> propertySources = ConfigurationPropertySources
+		Iterable<@Nullable ConfigurationPropertySource> propertySources = ConfigurationPropertySources
 			.from(new MapPropertySource("test", source));
 		propertySources.forEach(this.sources::add);
 		Bindable<JavaBean> target = Bindable.of(JavaBean.class);
@@ -330,7 +335,8 @@ class BinderTests {
 		BindResult<JavaBean> result = this.binder.bind("foo", Bindable.of(JavaBean.class), new BindHandler() {
 
 			@Override
-			public <T> Bindable<T> onStart(ConfigurationPropertyName name, Bindable<T> target, BindContext context) {
+			public <T> @Nullable Bindable<T> onStart(ConfigurationPropertyName name, Bindable<T> target,
+					BindContext context) {
 				return null;
 			}
 
@@ -372,15 +378,15 @@ class BinderTests {
 
 	static class JavaBean {
 
-		private String value;
+		private @Nullable String value;
 
 		private final List<String> items = Collections.emptyList();
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
-		void setValue(String value) {
+		void setValue(@Nullable String value) {
 			this.value = value;
 		}
 
@@ -433,13 +439,13 @@ class BinderTests {
 	@Validated
 	static class ResourceBean {
 
-		private Resource resource;
+		private @Nullable Resource resource;
 
-		Resource getResource() {
+		@Nullable Resource getResource() {
 			return this.resource;
 		}
 
-		void setResource(Resource resource) {
+		void setResource(@Nullable Resource resource) {
 			this.resource = resource;
 		}
 
@@ -447,13 +453,13 @@ class BinderTests {
 
 	static class CycleBean1 {
 
-		private CycleBean2 two;
+		private @Nullable CycleBean2 two;
 
-		CycleBean2 getTwo() {
+		@Nullable CycleBean2 getTwo() {
 			return this.two;
 		}
 
-		void setTwo(CycleBean2 two) {
+		void setTwo(@Nullable CycleBean2 two) {
 			this.two = two;
 		}
 
@@ -461,13 +467,13 @@ class BinderTests {
 
 	static class CycleBean2 {
 
-		private CycleBean1 one;
+		private @Nullable CycleBean1 one;
 
-		CycleBean1 getOne() {
+		@Nullable CycleBean1 getOne() {
 			return this.one;
 		}
 
-		void setOne(CycleBean1 one) {
+		void setOne(@Nullable CycleBean1 one) {
 			this.one = one;
 		}
 
@@ -475,13 +481,13 @@ class BinderTests {
 
 	static class GenericBean<T> {
 
-		private T bar;
+		private @Nullable T bar;
 
-		T getBar() {
+		@Nullable T getBar() {
 			return this.bar;
 		}
 
-		void setBar(T bar) {
+		void setBar(@Nullable T bar) {
 			this.bar = bar;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/BoundPropertiesTrackingBindHandlerTests.java

@@ -49,6 +49,7 @@ class BoundPropertiesTrackingBindHandlerTests {
 	private Binder binder;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private Consumer<ConfigurationProperty> consumer;
 
 	@BeforeEach

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/CollectionBinderTests.java

@@ -26,6 +26,7 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.context.properties.bind.BinderTests.ExampleEnum;
@@ -117,7 +118,9 @@ class CollectionBinderTests {
 		this.sources.add(source);
 		assertThatExceptionOfType(BindException.class).isThrownBy(() -> this.binder.bind("foo", INTEGER_LIST))
 			.satisfies((ex) -> {
-				Set<ConfigurationProperty> unbound = ((UnboundConfigurationPropertiesException) ex.getCause())
+				Throwable cause = ex.getCause();
+				assertThat(cause).isNotNull();
+				Set<ConfigurationProperty> unbound = ((UnboundConfigurationPropertiesException) cause)
 					.getUnboundProperties();
 				assertThat(unbound).singleElement().satisfies((property) -> {
 					assertThat(property.getName()).hasToString("foo[3]");
@@ -137,7 +140,9 @@ class CollectionBinderTests {
 		assertThatExceptionOfType(BindException.class)
 			.isThrownBy(() -> this.binder.bind("foo", Bindable.listOf(Name.class)))
 			.satisfies((ex) -> {
-				Set<ConfigurationProperty> unbound = ((UnboundConfigurationPropertiesException) ex.getCause())
+				Throwable cause = ex.getCause();
+				assertThat(cause).isNotNull();
+				Set<ConfigurationProperty> unbound = ((UnboundConfigurationPropertiesException) cause)
 					.getUnboundProperties();
 				assertThat(unbound).singleElement().satisfies((property) -> {
 					assertThat(property.getName()).hasToString("foo[1].missing");
@@ -171,7 +176,9 @@ class CollectionBinderTests {
 		Bindable<List<JavaBean>> target = Bindable.listOf(JavaBean.class);
 		assertThatExceptionOfType(BindException.class).isThrownBy(() -> this.binder.bind("foo", target))
 			.satisfies((ex) -> {
-				Set<ConfigurationProperty> unbound = ((UnboundConfigurationPropertiesException) ex.getCause())
+				Throwable cause = ex.getCause();
+				assertThat(cause).isNotNull();
+				Set<ConfigurationProperty> unbound = ((UnboundConfigurationPropertiesException) cause)
 					.getUnboundProperties();
 				assertThat(unbound).singleElement().satisfies((property) -> {
 					assertThat(property.getName()).hasToString("foo[4].value");
@@ -394,8 +401,10 @@ class CollectionBinderTests {
 		Bindable<BeanWithNestedCollection> target = Bindable.of(BeanWithNestedCollection.class);
 		BeanWithNestedCollection foo = this.binder.bind("foo", target).get();
 		assertThat(foo.getValue()).isEqualTo("one");
-		assertThat(foo.getFoos().get(0).getValue()).isEqualTo("two");
-		assertThat(foo.getFoos().get(1).getValue()).isEqualTo("three");
+		List<BeanWithNestedCollection> foos = foo.getFoos();
+		assertThat(foos).isNotNull();
+		assertThat(foos.get(0).getValue()).isEqualTo("two");
+		assertThat(foos.get(1).getValue()).isEqualTo("three");
 	}
 
 	@Test
@@ -465,7 +474,9 @@ class CollectionBinderTests {
 		source.put("foo.values[0]", "foo-bar,bar-baz");
 		this.sources.add(source);
 		BeanWithEnumSetCollection result = this.binder.bind("foo", Bindable.of(BeanWithEnumSetCollection.class)).get();
-		assertThat(result.getValues().get(0)).containsExactly(ExampleEnum.FOO_BAR, ExampleEnum.BAR_BAZ);
+		List<EnumSet<ExampleEnum>> values = result.getValues();
+		assertThat(values).isNotNull();
+		assertThat(values.get(0)).containsExactly(ExampleEnum.FOO_BAR, ExampleEnum.BAR_BAZ);
 	}
 
 	@Test
@@ -504,7 +515,7 @@ class CollectionBinderTests {
 
 		private Set<String> itemsSet = new LinkedHashSet<>();
 
-		private String string;
+		private @Nullable String string;
 
 		List<String> getItems() {
 			return this.items;
@@ -522,11 +533,11 @@ class CollectionBinderTests {
 			this.itemsSet = itemsSet;
 		}
 
-		String getString() {
+		@Nullable String getString() {
 			return this.string;
 		}
 
-		void setString(String string) {
+		void setString(@Nullable String string) {
 			this.string = string;
 		}
 
@@ -576,23 +587,23 @@ class CollectionBinderTests {
 
 	static class BeanWithNestedCollection {
 
-		private String value;
+		private @Nullable String value;
 
-		private List<BeanWithNestedCollection> foos;
+		private @Nullable List<BeanWithNestedCollection> foos;
 
-		List<BeanWithNestedCollection> getFoos() {
+		@Nullable List<BeanWithNestedCollection> getFoos() {
 			return this.foos;
 		}
 
-		void setFoos(List<BeanWithNestedCollection> foos) {
+		void setFoos(@Nullable List<BeanWithNestedCollection> foos) {
 			this.foos = foos;
 		}
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
-		void setValue(String value) {
+		void setValue(@Nullable String value) {
 			this.value = value;
 		}
 
@@ -600,13 +611,13 @@ class CollectionBinderTests {
 
 	static class ClonedArrayBean {
 
-		private String[] bar;
+		private String @Nullable [] bar;
 
-		String[] getBar() {
-			return this.bar.clone();
+		String @Nullable [] getBar() {
+			return (this.bar != null) ? this.bar.clone() : null;
 		}
 
-		void setBar(String[] bar) {
+		void setBar(String @Nullable [] bar) {
 			this.bar = bar;
 		}
 
@@ -614,13 +625,13 @@ class CollectionBinderTests {
 
 	static class BeanWithGetterException {
 
-		private List<String> values;
+		private @Nullable List<String> values;
 
-		void setValues(List<String> values) {
+		void setValues(@Nullable List<String> values) {
 			this.values = values;
 		}
 
-		List<String> getValues() {
+		@Nullable List<String> getValues() {
 			return Collections.unmodifiableList(this.values);
 		}
 
@@ -628,13 +639,13 @@ class CollectionBinderTests {
 
 	static class BeanWithEnumSetCollection {
 
-		private List<EnumSet<ExampleEnum>> values;
+		private @Nullable List<EnumSet<ExampleEnum>> values;
 
-		void setValues(List<EnumSet<ExampleEnum>> values) {
+		void setValues(@Nullable List<EnumSet<ExampleEnum>> values) {
 			this.values = values;
 		}
 
-		List<EnumSet<ExampleEnum>> getValues() {
+		@Nullable List<EnumSet<ExampleEnum>> getValues() {
 			return this.values;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/JavaBeanBinderTests.java

@@ -28,6 +28,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.context.properties.bind.JavaBeanBinder.Bean;
@@ -271,8 +272,10 @@ class JavaBeanBinderTests {
 		source.put("foo.value-bean.string-value", "foo");
 		this.sources.add(source);
 		ExampleNestedBean bean = this.binder.bind("foo", Bindable.of(ExampleNestedBean.class)).get();
-		assertThat(bean.getValueBean().getIntValue()).isEqualTo(123);
-		assertThat(bean.getValueBean().getStringValue()).isEqualTo("foo");
+		ExampleValueBean valueBean = bean.getValueBean();
+		assertThat(valueBean).isNotNull();
+		assertThat(valueBean.getIntValue()).isEqualTo(123);
+		assertThat(valueBean.getStringValue()).isEqualTo("foo");
 	}
 
 	@Test
@@ -505,8 +508,12 @@ class JavaBeanBinderTests {
 		source.put("foo.booleans[b].value", "true");
 		this.sources.add(source);
 		ExampleWithGenericMap bean = this.binder.bind("foo", Bindable.of(ExampleWithGenericMap.class)).get();
-		assertThat(bean.getIntegers().get("a").getValue()).isOne();
-		assertThat(bean.getBooleans().get("b").getValue()).isTrue();
+		GenericValue<Integer> a = bean.getIntegers().get("a");
+		assertThat(a).isNotNull();
+		assertThat(a.getValue()).isOne();
+		GenericValue<Boolean> b = bean.getBooleans().get("b");
+		assertThat(b).isNotNull();
+		assertThat(b.getValue()).isTrue();
 	}
 
 	@Test
@@ -524,7 +531,9 @@ class JavaBeanBinderTests {
 	void beanPropertiesPreferMatchingType() {
 		// gh-16206
 		ResolvableType type = ResolvableType.forClass(PropertyWithOverloadedSetter.class);
-		Bean<PropertyWithOverloadedSetter> bean = new Bean<>(type, type.resolve()) {
+		Class<?> resolvedType = type.resolve();
+		assertThat(resolvedType).isNotNull();
+		Bean<PropertyWithOverloadedSetter> bean = new Bean<>(type, resolvedType) {
 
 			@Override
 			protected void addProperties(Method[] declaredMethods, Field[] declaredFields) {
@@ -553,6 +562,7 @@ class JavaBeanBinderTests {
 
 		};
 		BeanProperty property = bean.getProperties().get("property");
+		assertThat(property).isNotNull();
 		PropertyWithOverloadedSetter target = new PropertyWithOverloadedSetter();
 		property.setValue(() -> target, "some string");
 	}
@@ -621,9 +631,9 @@ class JavaBeanBinderTests {
 
 		private long longValue;
 
-		private String stringValue;
+		private @Nullable String stringValue;
 
-		private ExampleEnum enumValue;
+		private @Nullable ExampleEnum enumValue;
 
 		int getIntValue() {
 			return this.intValue;
@@ -641,19 +651,19 @@ class JavaBeanBinderTests {
 			this.longValue = longValue;
 		}
 
-		String getStringValue() {
+		@Nullable String getStringValue() {
 			return this.stringValue;
 		}
 
-		void setStringValue(String stringValue) {
+		void setStringValue(@Nullable String stringValue) {
 			this.stringValue = stringValue;
 		}
 
-		ExampleEnum getEnumValue() {
+		@Nullable ExampleEnum getEnumValue() {
 			return this.enumValue;
 		}
 
-		void setEnumValue(ExampleEnum enumValue) {
+		void setEnumValue(@Nullable ExampleEnum enumValue) {
 			this.enumValue = enumValue;
 		}
 
@@ -662,13 +672,13 @@ class JavaBeanBinderTests {
 	static class ExampleRenamedPropertyBean {
 
 		@Name("public")
-		private String exampleProperty;
+		private @Nullable String exampleProperty;
 
-		String getExampleProperty() {
+		@Nullable String getExampleProperty() {
 			return this.exampleProperty;
 		}
 
-		void setExampleProperty(String exampleProperty) {
+		void setExampleProperty(@Nullable String exampleProperty) {
 			this.exampleProperty = exampleProperty;
 		}
 
@@ -700,13 +710,13 @@ class JavaBeanBinderTests {
 
 	static class ExampleMapBean {
 
-		private Map<ExampleEnum, Integer> map;
+		private @Nullable Map<ExampleEnum, Integer> map;
 
-		Map<ExampleEnum, Integer> getMap() {
+		@Nullable Map<ExampleEnum, Integer> getMap() {
 			return this.map;
 		}
 
-		void setMap(Map<ExampleEnum, Integer> map) {
+		void setMap(@Nullable Map<ExampleEnum, Integer> map) {
 			this.map = map;
 		}
 
@@ -714,13 +724,13 @@ class JavaBeanBinderTests {
 
 	static class ExampleListBean {
 
-		private List<ExampleEnum> list;
+		private @Nullable List<ExampleEnum> list;
 
-		List<ExampleEnum> getList() {
+		@Nullable List<ExampleEnum> getList() {
 			return this.list;
 		}
 
-		void setList(List<ExampleEnum> list) {
+		void setList(@Nullable List<ExampleEnum> list) {
 			this.list = list;
 		}
 
@@ -728,13 +738,13 @@ class JavaBeanBinderTests {
 
 	static class ExampleSetBean {
 
-		private Set<ExampleEnum> set;
+		private @Nullable Set<ExampleEnum> set;
 
-		Set<ExampleEnum> getSet() {
+		@Nullable Set<ExampleEnum> getSet() {
 			return this.set;
 		}
 
-		void setSet(Set<ExampleEnum> set) {
+		void setSet(@Nullable Set<ExampleEnum> set) {
 			this.set = set;
 		}
 
@@ -742,13 +752,13 @@ class JavaBeanBinderTests {
 
 	static class ExampleCollectionBean {
 
-		private Collection<ExampleEnum> collection;
+		private @Nullable Collection<ExampleEnum> collection;
 
-		Collection<ExampleEnum> getCollection() {
+		@Nullable Collection<ExampleEnum> getCollection() {
 			return this.collection;
 		}
 
-		void setCollection(Collection<ExampleEnum> collection) {
+		void setCollection(@Nullable Collection<ExampleEnum> collection) {
 			this.collection = collection;
 		}
 
@@ -797,13 +807,13 @@ class JavaBeanBinderTests {
 	static class ExampleCollectionBeanWithDelimiter {
 
 		@Delimiter("|")
-		private Collection<ExampleEnum> collection;
+		private @Nullable Collection<ExampleEnum> collection;
 
-		Collection<ExampleEnum> getCollection() {
+		@Nullable Collection<ExampleEnum> getCollection() {
 			return this.collection;
 		}
 
-		void setCollection(Collection<ExampleEnum> collection) {
+		void setCollection(@Nullable Collection<ExampleEnum> collection) {
 			this.collection = collection;
 		}
 
@@ -811,13 +821,13 @@ class JavaBeanBinderTests {
 
 	static class ExampleNestedBean {
 
-		private ExampleValueBean valueBean;
+		private @Nullable ExampleValueBean valueBean;
 
-		ExampleValueBean getValueBean() {
+		@Nullable ExampleValueBean getValueBean() {
 			return this.valueBean;
 		}
 
-		void setValueBean(ExampleValueBean valueBean) {
+		void setValueBean(@Nullable ExampleValueBean valueBean) {
 			this.valueBean = valueBean;
 		}
 
@@ -863,14 +873,14 @@ class JavaBeanBinderTests {
 
 	static class ExampleNestedSubclassBean extends ExampleNestedBean {
 
-		private ExampleValueSubclassBean valueBean;
+		private @Nullable ExampleValueSubclassBean valueBean;
 
 		@Override
-		ExampleValueSubclassBean getValueBean() {
+		@Nullable ExampleValueSubclassBean getValueBean() {
 			return this.valueBean;
 		}
 
-		void setValueBean(ExampleValueSubclassBean valueBean) {
+		void setValueBean(@Nullable ExampleValueSubclassBean valueBean) {
 			this.valueBean = valueBean;
 		}
 
@@ -892,17 +902,17 @@ class JavaBeanBinderTests {
 
 	static class ExampleWithNonDefaultConstructor {
 
-		private String value;
+		private @Nullable String value;
 
-		ExampleWithNonDefaultConstructor(String value) {
+		ExampleWithNonDefaultConstructor(@Nullable String value) {
 			this.value = value;
 		}
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
-		void setValue(String value) {
+		void setValue(@Nullable String value) {
 			this.value = value;
 		}
 
@@ -976,7 +986,7 @@ class JavaBeanBinderTests {
 
 		private int value;
 
-		private ExampleWithSelfReference self;
+		private @Nullable ExampleWithSelfReference self;
 
 		int getValue() {
 			return this.value;
@@ -986,11 +996,11 @@ class JavaBeanBinderTests {
 			this.value = value;
 		}
 
-		ExampleWithSelfReference getSelf() {
+		@Nullable ExampleWithSelfReference getSelf() {
 			return this.self;
 		}
 
-		void setSelf(ExampleWithSelfReference self) {
+		void setSelf(@Nullable ExampleWithSelfReference self) {
 			this.self = self;
 		}
 
@@ -998,13 +1008,13 @@ class JavaBeanBinderTests {
 
 	static class ExampleWithInvalidAccessors {
 
-		private String name;
+		private @Nullable String name;
 
-		String getName() {
+		@Nullable String getName() {
 			return this.name;
 		}
 
-		void setName(String name) {
+		void setName(@Nullable String name) {
 			this.name = name;
 		}
 
@@ -1020,15 +1030,15 @@ class JavaBeanBinderTests {
 
 	static class ExampleWithStaticAccessors {
 
-		private static String name;
+		private static @Nullable String name;
 
 		private int counter;
 
-		static String getName() {
+		static @Nullable String getName() {
 			return name;
 		}
 
-		static void setName(String name) {
+		static void setName(@Nullable String name) {
 			ExampleWithStaticAccessors.name = name;
 		}
 
@@ -1053,13 +1063,13 @@ class JavaBeanBinderTests {
 	static class ConverterAnnotatedExampleBean {
 
 		@DateTimeFormat(iso = DateTimeFormat.ISO.DATE)
-		private LocalDate date;
+		private @Nullable LocalDate date;
 
-		LocalDate getDate() {
+		@Nullable LocalDate getDate() {
 			return this.date;
 		}
 
-		void setDate(LocalDate date) {
+		void setDate(@Nullable LocalDate date) {
 			this.date = date;
 		}
 
@@ -1067,13 +1077,13 @@ class JavaBeanBinderTests {
 
 	static class ExampleWithPropertyEditorType {
 
-		private Class<? extends Throwable> value;
+		private @Nullable Class<? extends Throwable> value;
 
-		Class<? extends Throwable> getValue() {
+		@Nullable Class<? extends Throwable> getValue() {
 			return this.value;
 		}
 
-		void setValue(Class<? extends Throwable> value) {
+		void setValue(@Nullable Class<? extends Throwable> value) {
 			this.value = value;
 		}
 
@@ -1097,13 +1107,13 @@ class JavaBeanBinderTests {
 
 	static class GenericValue<T> {
 
-		private T value;
+		private @Nullable T value;
 
-		T getValue() {
+		@Nullable T getValue() {
 			return this.value;
 		}
 
-		void setValue(T value) {
+		void setValue(@Nullable T value) {
 			this.value = value;
 		}
 
@@ -1111,17 +1121,17 @@ class JavaBeanBinderTests {
 
 	static class PropertyWithOverloadedSetter {
 
-		private String property;
+		private @Nullable String property;
 
 		void setProperty(int property) {
 			this.property = String.valueOf(property);
 		}
 
-		void setProperty(String property) {
+		void setProperty(@Nullable String property) {
 			this.property = property;
 		}
 
-		String getProperty() {
+		@Nullable String getProperty() {
 			return this.property;
 		}
 
@@ -1143,13 +1153,13 @@ class JavaBeanBinderTests {
 
 	static class PackagePrivateSetterBean {
 
-		private String property;
+		private @Nullable String property;
 
-		String getProperty() {
+		@Nullable String getProperty() {
 			return this.property;
 		}
 
-		void setProperty(String property) {
+		void setProperty(@Nullable String property) {
 			this.property = property;
 		}
 
@@ -1225,13 +1235,13 @@ class JavaBeanBinderTests {
 
 	static class BridgeMethodsBase<T extends BridgeBaseType> {
 
-		private T value;
+		private @Nullable T value;
 
-		T getValue() {
+		@Nullable T getValue() {
 			return this.value;
 		}
 
-		void setValue(T value) {
+		void setValue(@Nullable T value) {
 			this.value = value;
 		}
 
@@ -1240,7 +1250,7 @@ class JavaBeanBinderTests {
 	static class BridgeMethods extends BridgeMethodsBase<BridgeType> {
 
 		@Override
-		BridgeType getValue() {
+		@Nullable BridgeType getValue() {
 			return super.getValue();
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/JavaBeanWithPublicConstructor.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.context.properties.bind;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Java bean with an additional public single-arg constructor.
  *
@@ -23,7 +25,7 @@ package org.springframework.boot.context.properties.bind;
  */
 public class JavaBeanWithPublicConstructor {
 
-	private String value;
+	private @Nullable String value;
 
 	public JavaBeanWithPublicConstructor() {
 	}
@@ -32,11 +34,11 @@ public class JavaBeanWithPublicConstructor {
 		setValue(value);
 	}
 
-	public String getValue() {
+	public @Nullable String getValue() {
 		return this.value;
 	}
 
-	public void setValue(String value) {
+	public void setValue(@Nullable String value) {
 		this.value = value;
 	}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/MapBinderTests.java

@@ -29,6 +29,7 @@ import java.util.Properties;
 import java.util.Set;
 import java.util.stream.Collectors;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.mockito.InOrder;
 import org.mockito.invocation.InvocationOnMock;
@@ -369,7 +370,9 @@ class MapBinderTests {
 		source.put("foo.bar[2].value", "c");
 		this.sources.add(source);
 		Map<String, List<JavaBean>> map = this.binder.bind("foo", target).get();
-		List<String> values = map.get("bar").stream().map(JavaBean::getValue).toList();
+		List<JavaBean> bar = map.get("bar");
+		assertThat(bar).isNotNull();
+		List<String> values = bar.stream().map(JavaBean::getValue).toList();
 		assertThat(values).containsExactly("a", "b", "c");
 
 	}
@@ -387,7 +390,9 @@ class MapBinderTests {
 		this.sources.add(new MockConfigurationPropertySource("foo.bar.pattern", "1", "line1"));
 		Bindable<Map<String, Foo>> target = Bindable.mapOf(String.class, Foo.class);
 		Map<String, Foo> map = this.binder.bind("foo", target).get();
-		assertThat(map.get("bar").getPattern()).isEqualTo("1");
+		Foo bar = map.get("bar");
+		assertThat(bar).isNotNull();
+		assertThat(bar.getPattern()).isEqualTo("1");
 	}
 
 	@Test
@@ -434,7 +439,9 @@ class MapBinderTests {
 		mockSource.put("foo.bar.baz[2].value", "c");
 		this.sources.add(mockSource);
 		Map<String, List<JavaBean>> map = this.binder.bind("foo", target).get();
-		List<String> values = map.get("bar.baz").stream().map(JavaBean::getValue).toList();
+		List<JavaBean> barBaz = map.get("bar.baz");
+		assertThat(barBaz).isNotNull();
+		List<String> values = barBaz.stream().map(JavaBean::getValue).toList();
 		assertThat(values).containsExactly("a", "b", "c");
 	}
 
@@ -495,8 +502,12 @@ class MapBinderTests {
 		this.sources.add(source);
 		BindResult<NestableFoo> foo = this.binder.bind("foo", NestableFoo.class);
 		assertThat(foo.get().getValue()).isNotNull();
-		assertThat(foo.get().getFoos().get("foo1").getValue()).isEqualTo("two");
-		assertThat(foo.get().getFoos().get("foo2").getValue()).isEqualTo("three");
+		NestableFoo foo1 = foo.get().getFoos().get("foo1");
+		assertThat(foo1).isNotNull();
+		assertThat(foo1.getValue()).isEqualTo("two");
+		NestableFoo foo2 = foo.get().getFoos().get("foo2");
+		assertThat(foo2).isNotNull();
+		assertThat(foo2.getValue()).isEqualTo("three");
 	}
 
 	@Test
@@ -611,8 +622,11 @@ class MapBinderTests {
 		source.put("foo.addresses.localhost[1]", "127.0.0.2");
 		this.sources.add(source);
 		MapWithWildcardProperties result = this.binder.bind("foo", Bindable.of(MapWithWildcardProperties.class)).get();
-		assertThat(result.getAddresses().get("localhost").stream().map(InetAddress::getHostAddress))
-			.containsExactly("127.0.0.1", "127.0.0.2");
+		Map<String, ? extends List<? extends InetAddress>> addresses = result.getAddresses();
+		assertThat(addresses).isNotNull();
+		List<? extends InetAddress> localhost = addresses.get("localhost");
+		assertThat(localhost).isNotNull();
+		assertThat(localhost.stream().map(InetAddress::getHostAddress)).containsExactly("127.0.0.1", "127.0.0.2");
 	}
 
 	@Test
@@ -670,20 +684,20 @@ class MapBinderTests {
 
 	static class Foo {
 
-		private String pattern;
+		private @Nullable String pattern;
 
 		Foo() {
 		}
 
-		Foo(String pattern) {
+		Foo(@Nullable String pattern) {
 			this.pattern = pattern;
 		}
 
-		String getPattern() {
+		@Nullable String getPattern() {
 			return this.pattern;
 		}
 
-		void setPattern(String pattern) {
+		void setPattern(@Nullable String pattern) {
 			this.pattern = pattern;
 		}
 
@@ -693,17 +707,17 @@ class MapBinderTests {
 
 		private final Map<String, NestableFoo> foos = new LinkedHashMap<>();
 
-		private String value;
+		private @Nullable String value;
 
 		Map<String, NestableFoo> getFoos() {
 			return this.foos;
 		}
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
-		void setValue(String value) {
+		void setValue(@Nullable String value) {
 			this.value = value;
 		}
 
@@ -762,13 +776,13 @@ class MapBinderTests {
 
 	static class BeanWithGetterException {
 
-		private Map<String, String> values;
+		private @Nullable Map<String, String> values;
 
-		void setValues(Map<String, String> values) {
+		void setValues(@Nullable Map<String, String> values) {
 			this.values = values;
 		}
 
-		Map<String, String> getValues() {
+		@Nullable Map<String, String> getValues() {
 			return Collections.unmodifiableMap(this.values);
 		}
 
@@ -776,13 +790,13 @@ class MapBinderTests {
 
 	static class MapWithWildcardProperties {
 
-		private Map<String, ? extends List<? extends InetAddress>> addresses;
+		private @Nullable Map<String, ? extends List<? extends InetAddress>> addresses;
 
-		Map<String, ? extends List<? extends InetAddress>> getAddresses() {
+		@Nullable Map<String, ? extends List<? extends InetAddress>> getAddresses() {
 			return this.addresses;
 		}
 
-		void setAddresses(Map<String, ? extends List<? extends InetAddress>> addresses) {
+		void setAddresses(@Nullable Map<String, ? extends List<? extends InetAddress>> addresses) {
 			this.addresses = addresses;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/PropertySourcesPlaceholdersResolverTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.context.properties.bind;
 import java.util.HashMap;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.env.Environment;
@@ -38,9 +39,10 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  */
 class PropertySourcesPlaceholdersResolverTests {
 
-	private PropertySourcesPlaceholdersResolver resolver;
+	private @Nullable PropertySourcesPlaceholdersResolver resolver;
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void placeholderResolverIfEnvironmentNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> new PropertySourcesPlaceholdersResolver((Environment) null))

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/ValueObjectBinderTests.java

@@ -28,6 +28,7 @@ import java.util.Optional;
 
 import com.jayway.jsonpath.JsonPath;
 import com.jayway.jsonpath.internal.CharacterIndex;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.context.properties.source.ConfigurationPropertyName;
@@ -733,9 +734,9 @@ class ValueObjectBinderTests {
 
 	static class NestedJavaBean {
 
-		private String value;
+		private @Nullable String value;
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
@@ -903,23 +904,23 @@ class ValueObjectBinderTests {
 
 	static class NonExtractableParameterName {
 
-		private String value;
+		private @Nullable String value;
 
-		private JsonPath jsonPath;
+		private @Nullable JsonPath jsonPath;
 
-		String getValue() {
+		@Nullable String getValue() {
 			return this.value;
 		}
 
-		void setValue(String value) {
+		void setValue(@Nullable String value) {
 			this.value = value;
 		}
 
-		JsonPath getJsonPath() {
+		@Nullable JsonPath getJsonPath() {
 			return this.jsonPath;
 		}
 
-		void setJsonPath(JsonPath jsonPath) {
+		void setJsonPath(@Nullable JsonPath jsonPath) {
 			this.jsonPath = jsonPath;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/handler/IgnoreTopLevelConverterNotFoundBindHandlerTests.java

@@ -20,6 +20,7 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -89,7 +90,7 @@ class IgnoreTopLevelConverterNotFoundBindHandlerTests {
 
 		private int foo;
 
-		private Map<String, String> map;
+		private @Nullable Map<String, String> map;
 
 		int getFoo() {
 			return this.foo;
@@ -99,11 +100,11 @@ class IgnoreTopLevelConverterNotFoundBindHandlerTests {
 			throw new IllegalStateException();
 		}
 
-		Map<String, String> getMap() {
+		@Nullable Map<String, String> getMap() {
 			return this.map;
 		}
 
-		void setMap(Map<String, String> map) {
+		void setMap(@Nullable Map<String, String> map) {
 			this.map = map;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/handler/NoUnboundElementsBindHandlerTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.context.properties.bind.handler;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.context.properties.bind.BindException;
@@ -42,7 +43,7 @@ class NoUnboundElementsBindHandlerTests {
 
 	private final List<ConfigurationPropertySource> sources = new ArrayList<>();
 
-	private Binder binder;
+	private @Nullable Binder binder;
 
 	@Test
 	void bindWhenNotUsingNoUnboundElementsHandlerShouldBind() {
@@ -73,11 +74,14 @@ class NoUnboundElementsBindHandlerTests {
 		source.put("example.baz", "bar");
 		this.sources.add(source);
 		this.binder = new Binder(this.sources);
-		assertThatExceptionOfType(BindException.class)
-			.isThrownBy(
-					() -> this.binder.bind("example", Bindable.of(Example.class), new NoUnboundElementsBindHandler()))
-			.satisfies((ex) -> assertThat(ex.getCause().getMessage())
-				.contains("The elements [example.baz] were left unbound"));
+		assertThatExceptionOfType(BindException.class).isThrownBy(() -> {
+			assertThat(this.binder).isNotNull();
+			this.binder.bind("example", Bindable.of(Example.class), new NoUnboundElementsBindHandler());
+		}).satisfies((ex) -> {
+			Throwable cause = ex.getCause();
+			assertThat(cause).isNotNull();
+			assertThat(cause.getMessage()).contains("The elements [example.baz] were left unbound");
+		});
 	}
 
 	@Test
@@ -126,11 +130,14 @@ class NoUnboundElementsBindHandlerTests {
 		source.put("example.foo[0]", "bar");
 		this.sources.add(source);
 		this.binder = new Binder(this.sources);
-		assertThatExceptionOfType(BindException.class)
-			.isThrownBy(
-					() -> this.binder.bind("example", Bindable.of(Example.class), new NoUnboundElementsBindHandler()))
-			.satisfies((ex) -> assertThat(ex.getCause().getMessage())
-				.contains("The elements [example.foo[0]] were left unbound"));
+		assertThatExceptionOfType(BindException.class).isThrownBy(() -> {
+			assertThat(this.binder).isNotNull();
+			this.binder.bind("example", Bindable.of(Example.class), new NoUnboundElementsBindHandler());
+		}).satisfies((ex) -> {
+			Throwable cause = ex.getCause();
+			assertThat(cause).isNotNull();
+			assertThat(cause.getMessage()).contains("The elements [example.foo[0]] were left unbound");
+		});
 	}
 
 	@Test
@@ -148,7 +155,9 @@ class NoUnboundElementsBindHandlerTests {
 		NoUnboundElementsBindHandler handler = new NoUnboundElementsBindHandler();
 		ExampleWithNestedList bound = this.binder.bind("example", Bindable.of(ExampleWithNestedList.class), handler)
 			.get();
-		assertThat(bound.getNested().get(0).getStringValue()).isEqualTo("bar");
+		List<Nested> nested = bound.getNested();
+		assertThat(nested).isNotNull();
+		assertThat(nested.get(0).getStringValue()).isEqualTo("bar");
 	}
 
 	@Test
@@ -162,22 +171,25 @@ class NoUnboundElementsBindHandlerTests {
 		this.sources.add(source1);
 		this.sources.add(source2);
 		this.binder = new Binder(this.sources);
-		assertThatExceptionOfType(BindException.class)
-			.isThrownBy(() -> this.binder.bind("example", Bindable.of(ExampleWithNestedList.class),
-					new NoUnboundElementsBindHandler()))
-			.satisfies((ex) -> assertThat(ex.getCause().getMessage())
-				.contains("The elements [example.nested[1].invalid] were left unbound"));
+		assertThatExceptionOfType(BindException.class).isThrownBy(() -> {
+			assertThat(this.binder).isNotNull();
+			this.binder.bind("example", Bindable.of(ExampleWithNestedList.class), new NoUnboundElementsBindHandler());
+		}).satisfies((ex) -> {
+			Throwable cause = ex.getCause();
+			assertThat(cause).isNotNull();
+			assertThat(cause.getMessage()).contains("The elements [example.nested[1].invalid] were left unbound");
+		});
 	}
 
 	static class Example {
 
-		private String foo;
+		private @Nullable String foo;
 
-		String getFoo() {
+		@Nullable String getFoo() {
 			return this.foo;
 		}
 
-		void setFoo(String foo) {
+		void setFoo(@Nullable String foo) {
 			this.foo = foo;
 		}
 
@@ -185,13 +197,13 @@ class NoUnboundElementsBindHandlerTests {
 
 	static class ExampleWithList {
 
-		private List<String> foo;
+		private @Nullable List<String> foo;
 
-		List<String> getFoo() {
+		@Nullable List<String> getFoo() {
 			return this.foo;
 		}
 
-		void setFoo(List<String> foo) {
+		void setFoo(@Nullable List<String> foo) {
 			this.foo = foo;
 		}
 
@@ -199,13 +211,13 @@ class NoUnboundElementsBindHandlerTests {
 
 	static class ExampleWithNestedList {
 
-		private List<Nested> nested;
+		private @Nullable List<Nested> nested;
 
-		List<Nested> getNested() {
+		@Nullable List<Nested> getNested() {
 			return this.nested;
 		}
 
-		void setNested(List<Nested> nested) {
+		void setNested(@Nullable List<Nested> nested) {
 			this.nested = nested;
 		}
 
@@ -213,33 +225,33 @@ class NoUnboundElementsBindHandlerTests {
 
 	static class Nested {
 
-		private String stringValue;
+		private @Nullable String stringValue;
 
-		private Integer intValue;
+		private @Nullable Integer intValue;
 
-		private OtherNested otherNested;
+		private @Nullable OtherNested otherNested;
 
-		String getStringValue() {
+		@Nullable String getStringValue() {
 			return this.stringValue;
 		}
 
-		void setStringValue(String value) {
+		void setStringValue(@Nullable String value) {
 			this.stringValue = value;
 		}
 
-		Integer getIntValue() {
+		@Nullable Integer getIntValue() {
 			return this.intValue;
 		}
 
-		void setIntValue(Integer intValue) {
+		void setIntValue(@Nullable Integer intValue) {
 			this.intValue = intValue;
 		}
 
-		OtherNested getOtherNested() {
+		@Nullable OtherNested getOtherNested() {
 			return this.otherNested;
 		}
 
-		void setOtherNested(OtherNested otherNested) {
+		void setOtherNested(@Nullable OtherNested otherNested) {
 			this.otherNested = otherNested;
 		}
 
@@ -247,13 +259,13 @@ class NoUnboundElementsBindHandlerTests {
 
 	static class OtherNested {
 
-		private String baz;
+		private @Nullable String baz;
 
-		String getBaz() {
+		@Nullable String getBaz() {
 			return this.baz;
 		}
 
-		void setBaz(String baz) {
+		void setBaz(@Nullable String baz) {
 			this.baz = baz;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/validation/BindValidationExceptionTests.java

@@ -31,6 +31,7 @@ import static org.mockito.Mockito.mock;
 class BindValidationExceptionTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenValidationErrorsIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new BindValidationException(null))
 			.withMessageContaining("'validationErrors' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/validation/ValidationBindHandlerTests.java

@@ -25,6 +25,7 @@ import java.util.Set;
 import jakarta.validation.Valid;
 import jakarta.validation.constraints.Min;
 import jakarta.validation.constraints.NotNull;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -268,7 +269,9 @@ class ValidationBindHandlerTests {
 			action.run();
 		}
 		catch (BindException ex) {
-			return (BindValidationException) ex.getCause();
+			Throwable cause = ex.getCause();
+			assertThat(cause).isNotNull();
+			return (BindValidationException) cause;
 		}
 		throw new IllegalStateException("Did not throw");
 	}
@@ -341,19 +344,20 @@ class ValidationBindHandlerTests {
 
 	static class ExampleNested {
 
-		private String name;
+		private @Nullable String name;
 
 		@Min(5)
 		private int age;
 
 		@NotNull
+		@SuppressWarnings("NullAway.Init")
 		private String address;
 
-		String getName() {
+		@Nullable String getName() {
 			return this.name;
 		}
 
-		void setName(String name) {
+		void setName(@Nullable String name) {
 			this.name = name;
 		}
 
@@ -423,13 +427,13 @@ class ValidationBindHandlerTests {
 
 	static class ExampleMapValue {
 
-		private String number;
+		private @Nullable String number;
 
-		String getNumber() {
+		@Nullable String getNumber() {
 			return this.number;
 		}
 
-		void setNumber(String number) {
+		void setNumber(@Nullable String number) {
 			this.number = number;
 		}
 
@@ -437,14 +441,14 @@ class ValidationBindHandlerTests {
 
 	static class TestHandler extends AbstractBindHandler {
 
-		private final Object result;
+		private final @Nullable Object result;
 
-		TestHandler(Object result) {
+		TestHandler(@Nullable Object result) {
 			this.result = result;
 		}
 
 		@Override
-		public Object onFailure(ConfigurationPropertyName name, Bindable<?> target, BindContext context,
+		public @Nullable Object onFailure(ConfigurationPropertyName name, Bindable<?> target, BindContext context,
 				Exception error) throws Exception {
 			return this.result;
 		}

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/validation/ValidationErrorsTests.java

@@ -45,6 +45,7 @@ class ValidationErrorsTests {
 	private static final ConfigurationPropertyName NAME = ConfigurationPropertyName.of("foo");
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenNameIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> new ValidationErrors(null, Collections.emptySet(), Collections.emptyList()))
@@ -52,12 +53,14 @@ class ValidationErrorsTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenBoundPropertiesIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ValidationErrors(NAME, null, Collections.emptyList()))
 			.withMessageContaining("'boundProperties' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenErrorsIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ValidationErrors(NAME, Collections.emptySet(), null))
 			.withMessageContaining("'errors' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/AliasedConfigurationPropertySourceTests.java

@@ -18,6 +18,7 @@ package org.springframework.boot.context.properties.source;
 
 import java.util.Collections;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -98,7 +99,7 @@ class AliasedConfigurationPropertySourceTests {
 			.isEqualTo(ConfigurationPropertyState.PRESENT);
 	}
 
-	private Object getValue(ConfigurationPropertySource source, String name) {
+	private @Nullable Object getValue(ConfigurationPropertySource source, String name) {
 		ConfigurationProperty property = source.getConfigurationProperty(ConfigurationPropertyName.of(name));
 		return (property != null) ? property.getValue() : null;
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyCachingTests.java

@@ -61,6 +61,7 @@ class ConfigurationPropertyCachingTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void getFromSourcesWhenSourcesIsNullThrowsException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> ConfigurationPropertyCaching.get((Iterable<ConfigurationPropertySource>) null))

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameAliasesTests.java

@@ -30,6 +30,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 class ConfigurationPropertyNameAliasesTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWithStringWhenNullNameShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigurationPropertyNameAliases((String) null))
 			.withMessageContaining("'name' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyNameTests.java

@@ -40,6 +40,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 class ConfigurationPropertyNameTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void ofNameShouldNotBeNull() {
 		assertThatIllegalArgumentException().isThrownBy(() -> ConfigurationPropertyName.of(null))
 			.withMessageContaining("'name' must not be null");
@@ -231,6 +232,7 @@ class ConfigurationPropertyNameTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void adaptWhenNameIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> ConfigurationPropertyName.adapt(null, '.'))
 			.withMessageContaining("Name must not be null");

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertySourceTests.java

@@ -35,8 +35,10 @@ class ConfigurationPropertySourceTests {
 		MockPropertySource source = new MockPropertySource();
 		source.setProperty("spring", "boot");
 		ConfigurationPropertySource adapted = ConfigurationPropertySource.from(source);
-		assertThat(adapted.getConfigurationProperty(ConfigurationPropertyName.of("spring")).getValue())
-			.isEqualTo("boot");
+		assertThat(adapted).isNotNull();
+		ConfigurationProperty spring = adapted.getConfigurationProperty(ConfigurationPropertyName.of("spring"));
+		assertThat(spring).isNotNull();
+		assertThat(spring.getValue()).isEqualTo("boot");
 	}
 
 	@Test

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertySourcesCachingTests.java

@@ -20,6 +20,7 @@ import java.time.Duration;
 import java.util.ArrayList;
 import java.util.List;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -108,7 +109,7 @@ class ConfigurationPropertySourcesCachingTests {
 		new ConfigurationPropertySourcesCaching(null).enable();
 	}
 
-	private ConfigurationPropertyCaching getCaching(int index) {
+	private @Nullable ConfigurationPropertyCaching getCaching(int index) {
 		return CachingConfigurationPropertySource.find(this.sources.get(index));
 	}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertySourcesPropertyResolverTests.java

@@ -20,6 +20,7 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.core.convert.ConversionFailedException;
@@ -165,7 +166,7 @@ class ConfigurationPropertySourcesPropertyResolverTests {
 		private final Map<String, AtomicInteger> counts = new HashMap<>();
 
 		@Override
-		public Object getProperty(String name) {
+		public @Nullable Object getProperty(String name) {
 			incrementCount(name);
 			return super.getProperty(name);
 		}

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertySourcesTests.java

@@ -22,6 +22,7 @@ import java.util.Map;
 import java.util.concurrent.TimeUnit;
 import java.util.function.Function;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Disabled;
 import org.junit.jupiter.api.Test;
 
@@ -129,7 +130,7 @@ class ConfigurationPropertySourcesTests {
 		sources.addFirst(new PropertySource<Environment>("env", environment) {
 
 			@Override
-			public String getProperty(String key) {
+			public @Nullable String getProperty(String key) {
 				return this.source.getProperty(key);
 			}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyStateTests.java

@@ -33,12 +33,14 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 class ConfigurationPropertyStateTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void searchWhenIterableIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> ConfigurationPropertyState.search(null, (e) -> true))
 			.withMessageContaining("'source' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void searchWhenPredicateIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> ConfigurationPropertyState.search(Collections.emptyList(), null))

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/ConfigurationPropertyTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.context.properties.source;
 
+import java.util.Objects;
+
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.origin.Origin;
@@ -36,15 +38,18 @@ class ConfigurationPropertyTests {
 
 	private static final ConfigurationPropertyName NAME = ConfigurationPropertyName.of("foo");
 
-	private final ConfigurationPropertySource source = ConfigurationPropertySource.from(mock(PropertySource.class));
+	private final ConfigurationPropertySource source = Objects
+		.requireNonNull(ConfigurationPropertySource.from(mock(PropertySource.class)));
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenNameIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigurationProperty(null, "bar", null))
 			.withMessageContaining("'name' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenValueIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new ConfigurationProperty(NAME, null, null))
 			.withMessageContaining("'value' must not be null");

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/FilteredConfigurationPropertiesSourceTests.java

@@ -32,6 +32,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 class FilteredConfigurationPropertiesSourceTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenSourceIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> new FilteredConfigurationPropertiesSource(null, Objects::nonNull))
@@ -39,6 +40,7 @@ class FilteredConfigurationPropertiesSourceTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenFilterIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> new FilteredConfigurationPropertiesSource(new MockConfigurationPropertySource(), null))
@@ -50,10 +52,16 @@ class FilteredConfigurationPropertiesSourceTests {
 		ConfigurationPropertySource source = createTestSource();
 		ConfigurationPropertySource filtered = source.filter(this::noBrackets);
 		ConfigurationPropertyName name = ConfigurationPropertyName.of("a");
-		assertThat(source.getConfigurationProperty(name).getValue()).isEqualTo("1");
-		assertThat(filtered.getConfigurationProperty(name).getValue()).isEqualTo("1");
+		ConfigurationProperty configurationProperty = source.getConfigurationProperty(name);
+		assertThat(configurationProperty).isNotNull();
+		assertThat(configurationProperty.getValue()).isEqualTo("1");
+		ConfigurationProperty configurationProperty2 = filtered.getConfigurationProperty(name);
+		assertThat(configurationProperty2).isNotNull();
+		assertThat(configurationProperty2.getValue()).isEqualTo("1");
 		ConfigurationPropertyName bracketName = ConfigurationPropertyName.of("a[1]");
-		assertThat(source.getConfigurationProperty(bracketName).getValue()).isEqualTo("2");
+		ConfigurationProperty configurationProperty3 = source.getConfigurationProperty(bracketName);
+		assertThat(configurationProperty3).isNotNull();
+		assertThat(configurationProperty3.getValue()).isEqualTo("2");
 		assertThat(filtered.getConfigurationProperty(bracketName)).isNull();
 	}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/FilteredIterableConfigurationPropertiesSourceTests.java

@@ -62,7 +62,9 @@ class FilteredIterableConfigurationPropertiesSourceTests extends FilteredConfigu
 		IterableConfigurationPropertySource testSource = (IterableConfigurationPropertySource) createTestSource();
 		Map<String, Object> map = new LinkedHashMap<>();
 		for (ConfigurationPropertyName name : testSource) {
-			map.put(name.toString(), testSource.getConfigurationProperty(name).getValue());
+			ConfigurationProperty configurationProperty = testSource.getConfigurationProperty(name);
+			assertThat(configurationProperty).isNotNull();
+			map.put(name.toString(), configurationProperty.getValue());
 		}
 		PropertySource<?> propertySource = new OriginTrackedMapPropertySource("test", map, true);
 		SpringConfigurationPropertySource source = SpringConfigurationPropertySource.from(propertySource);
@@ -79,7 +81,9 @@ class FilteredIterableConfigurationPropertiesSourceTests extends FilteredConfigu
 		IterableConfigurationPropertySource testSource = (IterableConfigurationPropertySource) createTestSource();
 		Map<String, Object> map = new LinkedHashMap<>();
 		for (ConfigurationPropertyName name : testSource) {
-			map.put(name.toString(), testSource.getConfigurationProperty(name).getValue());
+			ConfigurationProperty configurationProperty = testSource.getConfigurationProperty(name);
+			assertThat(configurationProperty).isNotNull();
+			map.put(name.toString(), configurationProperty.getValue());
 		}
 		PropertySource<?> propertySource = new OriginTrackedMapPropertySource("test", map, true);
 		SpringConfigurationPropertySource source = SpringConfigurationPropertySource.from(propertySource);

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/KnownAncestorsConfigurationPropertySource.java

@@ -19,6 +19,8 @@ package org.springframework.boot.context.properties.source;
 import java.util.HashMap;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import static org.assertj.core.api.Assertions.assertThat;
 
 class KnownAncestorsConfigurationPropertySource implements ConfigurationPropertySource {
@@ -26,7 +28,7 @@ class KnownAncestorsConfigurationPropertySource implements ConfigurationProperty
 	private final Map<ConfigurationPropertyName, ConfigurationPropertyState> ancestors = new HashMap<>();
 
 	@Override
-	public ConfigurationProperty getConfigurationProperty(ConfigurationPropertyName name) {
+	public @Nullable ConfigurationProperty getConfigurationProperty(ConfigurationPropertyName name) {
 		return null;
 	}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/MapConfigurationPropertySourceTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.context.properties.source;
 import java.util.LinkedHashMap;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -33,6 +34,7 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
 class MapConfigurationPropertySourceTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenMapIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new MapConfigurationPropertySource(null))
 			.withMessageContaining("'map' must not be null");
@@ -49,6 +51,7 @@ class MapConfigurationPropertySourceTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void putAllWhenMapIsNullShouldThrowException() {
 		MapConfigurationPropertySource source = new MapConfigurationPropertySource();
 		assertThatIllegalArgumentException().isThrownBy(() -> source.putAll(null))
@@ -101,7 +104,7 @@ class MapConfigurationPropertySourceTests {
 
 	}
 
-	private Object getValue(ConfigurationPropertySource source, String name) {
+	private @Nullable Object getValue(ConfigurationPropertySource source, String name) {
 		ConfigurationProperty property = source.getConfigurationProperty(ConfigurationPropertyName.of(name));
 		return (property != null) ? property.getValue() : null;
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/MockConfigurationPropertySource.java

@@ -21,6 +21,8 @@ import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.stream.Stream;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.origin.MockOrigin;
 import org.springframework.boot.origin.OriginTrackedValue;
 
@@ -41,7 +43,7 @@ public class MockConfigurationPropertySource implements IterableConfigurationPro
 		this(configurationPropertyName, value, null);
 	}
 
-	public MockConfigurationPropertySource(String configurationPropertyName, Object value, String origin) {
+	public MockConfigurationPropertySource(String configurationPropertyName, Object value, @Nullable String origin) {
 		put(ConfigurationPropertyName.of(configurationPropertyName),
 				OriginTrackedValue.of(value, MockOrigin.of(origin)));
 	}
@@ -82,7 +84,7 @@ public class MockConfigurationPropertySource implements IterableConfigurationPro
 	}
 
 	@Override
-	public ConfigurationProperty getConfigurationProperty(ConfigurationPropertyName name) {
+	public @Nullable ConfigurationProperty getConfigurationProperty(ConfigurationPropertyName name) {
 		OriginTrackedValue result = this.map.get(name);
 		if (result == null) {
 			result = findValue(name);
@@ -90,7 +92,7 @@ public class MockConfigurationPropertySource implements IterableConfigurationPro
 		return ConfigurationProperty.of(name, result);
 	}
 
-	private OriginTrackedValue findValue(ConfigurationPropertyName name) {
+	private @Nullable OriginTrackedValue findValue(ConfigurationPropertyName name) {
 		return this.map.get(name);
 	}
 
@@ -102,7 +104,7 @@ public class MockConfigurationPropertySource implements IterableConfigurationPro
 		}
 
 		@Override
-		public ConfigurationProperty getConfigurationProperty(ConfigurationPropertyName name) {
+		public @Nullable ConfigurationProperty getConfigurationProperty(ConfigurationPropertyName name) {
 			return MockConfigurationPropertySource.this.getConfigurationProperty(name);
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/MutuallyExclusiveConfigurationPropertiesExceptionTests.java

@@ -35,6 +35,7 @@ import static org.assertj.core.api.Assertions.assertThatNoException;
 class MutuallyExclusiveConfigurationPropertiesExceptionTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenConfiguredNamesIsNullThrowsException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> new MutuallyExclusiveConfigurationPropertiesException(null, Arrays.asList("a", "b")))
@@ -50,6 +51,7 @@ class MutuallyExclusiveConfigurationPropertiesExceptionTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenMutuallyExclusiveNamesIsNullThrowsException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> new MutuallyExclusiveConfigurationPropertiesException(Arrays.asList("a", "b"), null))

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/PrefixedConfigurationPropertySourceTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.boot.context.properties.source;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -82,12 +83,12 @@ class PrefixedConfigurationPropertySourceTests {
 		assertThat(prefixed).isSameAs(source);
 	}
 
-	private ConfigurationPropertyName getName(ConfigurationPropertySource source, String name) {
+	private @Nullable ConfigurationPropertyName getName(ConfigurationPropertySource source, String name) {
 		ConfigurationProperty property = source.getConfigurationProperty(ConfigurationPropertyName.of(name));
 		return (property != null) ? property.getName() : null;
 	}
 
-	private Object getValue(ConfigurationPropertySource source, String name) {
+	private @Nullable Object getValue(ConfigurationPropertySource source, String name) {
 		ConfigurationProperty property = source.getConfigurationProperty(ConfigurationPropertyName.of(name));
 		return (property != null) ? property.getValue() : null;
 	}

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/SoftReferenceConfigurationPropertyCacheTests.java

@@ -22,6 +22,7 @@ import java.time.Instant;
 import java.time.ZoneOffset;
 import java.util.concurrent.atomic.AtomicInteger;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.context.properties.source.ConfigurationPropertyCaching.CacheOverride;
@@ -186,14 +187,14 @@ class SoftReferenceConfigurationPropertyCacheTests {
 	 */
 	class TestSoftReferenceConfigurationPropertyCache extends SoftReferenceConfigurationPropertyCache<Value> {
 
-		private Value value;
+		private @Nullable Value value;
 
 		TestSoftReferenceConfigurationPropertyCache(boolean neverExpire) {
 			super(neverExpire);
 		}
 
 		@Override
-		protected Value getValue() {
+		protected @Nullable Value getValue() {
 			return this.value;
 		}
 

core/spring-boot/src/test/java/org/springframework/boot/context/properties/source/SpringConfigurationPropertySourceTests.java

@@ -20,6 +20,7 @@ import java.util.LinkedHashMap;
 import java.util.Locale;
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import org.springframework.boot.env.RandomValuePropertySource;
@@ -41,6 +42,7 @@ import static org.mockito.Mockito.mock;
 class SpringConfigurationPropertySourceTests {
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenPropertySourceIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> new SpringConfigurationPropertySource(null, false, mock(PropertyMapper.class)))
@@ -59,7 +61,9 @@ class SpringConfigurationPropertySourceTests {
 		mapper.addFromConfigurationProperty(name, "key2");
 		SpringConfigurationPropertySource adapter = new SpringConfigurationPropertySource(propertySource, false,
 				mapper);
-		assertThat(adapter.getConfigurationProperty(name).getValue()).isEqualTo("value2");
+		ConfigurationProperty configurationProperty = adapter.getConfigurationProperty(name);
+		assertThat(configurationProperty).isNotNull();
+		assertThat(configurationProperty.getValue()).isEqualTo("value2");
 	}
 
 	@Test
@@ -73,6 +77,7 @@ class SpringConfigurationPropertySourceTests {
 		SpringConfigurationPropertySource adapter = new SpringConfigurationPropertySource(propertySource, false,
 				mapper);
 		ConfigurationProperty configurationProperty = adapter.getConfigurationProperty(name);
+		assertThat(configurationProperty).isNotNull();
 		assertThat(configurationProperty.getOrigin()).hasToString("\"key\" from property source \"test\"");
 		assertThat(configurationProperty.getSource()).isEqualTo(adapter);
 	}
@@ -87,7 +92,9 @@ class SpringConfigurationPropertySourceTests {
 		mapper.addFromConfigurationProperty(name, "key");
 		SpringConfigurationPropertySource adapter = new SpringConfigurationPropertySource(propertySource, false,
 				mapper);
-		assertThat(adapter.getConfigurationProperty(name).getOrigin()).hasToString("TestOrigin key");
+		ConfigurationProperty configurationProperty = adapter.getConfigurationProperty(name);
+		assertThat(configurationProperty).isNotNull();
+		assertThat(configurationProperty.getOrigin()).hasToString("TestOrigin key");
 	}
 
 	@Test
@@ -102,6 +109,7 @@ class SpringConfigurationPropertySourceTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void fromWhenPropertySourceIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> SpringConfigurationPropertySource.from(null))
 			.withMessageContaining("'source' must not be null");
@@ -112,7 +120,7 @@ class SpringConfigurationPropertySourceTests {
 		PropertySource<?> propertySource = new PropertySource<>("test", new Object()) {
 
 			@Override
-			public Object getProperty(String name) {
+			public @Nullable Object getProperty(String name) {
 				return null;
 			}
 
@@ -242,7 +250,7 @@ class SpringConfigurationPropertySourceTests {
 		}
 
 		@Override
-		public Object getProperty(String name) {
+		public @Nullable Object getProperty(String name) {
 			name = name.toLowerCase(Locale.ROOT);
 			if (!name.startsWith(this.prefix)) {
 				return null;
@@ -267,7 +275,7 @@ class SpringConfigurationPropertySourceTests {
 		}
 
 		@Override
-		public Object getProperty(String name) {
+		public @Nullable Object getProperty(String name) {
 			return this.propertySource.getProperty(name);
 		}