Add nullability annotations to tests in core/spring-boot-test-autoconfigure

See gh-47263

core/spring-boot-test-autoconfigure/build.gradle

@@ -38,3 +38,7 @@ dependencies {
 	testRuntimeOnly("org.aspectj:aspectjrt")
 	testRuntimeOnly("org.aspectj:aspectjweaver")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}

core/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/ImportsContextCustomizerFactoryWithAutoConfigurationTests.java

@@ -19,6 +19,7 @@ package org.springframework.boot.test.autoconfigure;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 import org.junit.platform.engine.discovery.DiscoverySelectors;
 import org.junit.platform.launcher.Launcher;
@@ -44,7 +45,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 class ImportsContextCustomizerFactoryWithAutoConfigurationTests {
 
-	static ApplicationContext contextFromTest;
+	static @Nullable ApplicationContext contextFromTest;
 
 	@Test
 	void testClassesThatHaveSameAnnotationsShareAContext() {

core/spring-boot-test-autoconfigure/src/test/java/org/springframework/boot/test/autoconfigure/OverrideAutoConfigurationContextCustomizerFactoryTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.boot.test.autoconfigure;
 
+import java.util.Collections;
+
 import org.junit.jupiter.api.Test;
 
 import org.springframework.test.context.ContextCustomizer;
@@ -33,26 +35,31 @@ class OverrideAutoConfigurationContextCustomizerFactoryTests {
 
 	@Test
 	void getContextCustomizerWhenHasNoAnnotationShouldReturnNull() {
-		ContextCustomizer customizer = this.factory.createContextCustomizer(NoAnnotation.class, null);
+		ContextCustomizer customizer = this.factory.createContextCustomizer(NoAnnotation.class,
+				Collections.emptyList());
 		assertThat(customizer).isNull();
 	}
 
 	@Test
 	void getContextCustomizerWhenHasAnnotationEnabledTrueShouldReturnNull() {
-		ContextCustomizer customizer = this.factory.createContextCustomizer(WithAnnotationEnabledTrue.class, null);
+		ContextCustomizer customizer = this.factory.createContextCustomizer(WithAnnotationEnabledTrue.class,
+				Collections.emptyList());
 		assertThat(customizer).isNull();
 	}
 
 	@Test
 	void getContextCustomizerWhenHasAnnotationEnabledFalseShouldReturnCustomizer() {
-		ContextCustomizer customizer = this.factory.createContextCustomizer(WithAnnotationEnabledFalse.class, null);
+		ContextCustomizer customizer = this.factory.createContextCustomizer(WithAnnotationEnabledFalse.class,
+				Collections.emptyList());
 		assertThat(customizer).isNotNull();
 	}
 
 	@Test
 	void hashCodeAndEquals() {
-		ContextCustomizer customizer1 = this.factory.createContextCustomizer(WithAnnotationEnabledFalse.class, null);
-		ContextCustomizer customizer2 = this.factory.createContextCustomizer(WithSameAnnotation.class, null);
+		ContextCustomizer customizer1 = this.factory.createContextCustomizer(WithAnnotationEnabledFalse.class,
+				Collections.emptyList());
+		ContextCustomizer customizer2 = this.factory.createContextCustomizer(WithSameAnnotation.class,
+				Collections.emptyList());
 		assertThat(customizer1).hasSameHashCodeAs(customizer2);
 		assertThat(customizer1).isEqualTo(customizer1).isEqualTo(customizer2);
 	}