diff --git a/module/spring-boot-restclient/build.gradle b/module/spring-boot-restclient/build.gradle
index b156e4ad5b7..033bb26e76f 100644
--- a/module/spring-boot-restclient/build.gradle
+++ b/module/spring-boot-restclient/build.gradle
@@ -45,3 +45,7 @@ dependencies {
 	testRuntimeOnly("jakarta.servlet:jakarta.servlet-api")
 	testRuntimeOnly("org.springframework:spring-webflux")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}
diff --git a/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/RestTemplateBuilderTests.java b/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/RestTemplateBuilderTests.java
index 53c4a532bbf..34ba6f5037e 100644
--- a/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/RestTemplateBuilderTests.java
+++ b/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/RestTemplateBuilderTests.java
@@ -81,12 +81,15 @@ class RestTemplateBuilderTests {
 	private final RestTemplateBuilder builder = new RestTemplateBuilder();
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private HttpMessageConverter<Object> messageConverter;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ClientHttpRequestInterceptor interceptor;
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWhenCustomizersAreNullShouldThrowException() {
 		RestTemplateCustomizer[] customizers = null;
 		assertThatIllegalArgumentException().isThrownBy(() -> new RestTemplateBuilder(customizers))
@@ -134,6 +137,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void messageConvertersWhenConvertersAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.messageConverters((HttpMessageConverter<?>[]) null))
@@ -141,6 +145,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void messageConvertersCollectionWhenConvertersAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.messageConverters((Set<HttpMessageConverter<?>>) null))
@@ -162,6 +167,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void additionalMessageConvertersWhenConvertersAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.additionalMessageConverters((HttpMessageConverter<?>[]) null))
@@ -169,6 +175,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void additionalMessageConvertersCollectionWhenConvertersAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.additionalMessageConverters((Set<HttpMessageConverter<?>>) null))
@@ -199,6 +206,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void interceptorsWhenInterceptorsAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.interceptors((ClientHttpRequestInterceptor[]) null))
@@ -206,6 +214,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void interceptorsCollectionWhenInterceptorsAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.interceptors((Set<ClientHttpRequestInterceptor>) null))
@@ -227,6 +236,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void additionalInterceptorsWhenInterceptorsAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.additionalInterceptors((ClientHttpRequestInterceptor[]) null))
@@ -234,6 +244,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void additionalInterceptorsCollectionWhenInterceptorsAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.additionalInterceptors((Set<ClientHttpRequestInterceptor>) null))
@@ -248,6 +259,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void requestFactoryClassWhenFactoryIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.requestFactory((Class<ClientHttpRequestFactory>) null))
@@ -267,6 +279,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void requestFactoryWhenSupplierIsNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.requestFactory((Supplier<ClientHttpRequestFactory>) null))
@@ -281,6 +294,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void uriTemplateHandlerWhenHandlerIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> this.builder.uriTemplateHandler(null))
 			.withMessageContaining("'uriTemplateHandler' must not be null");
@@ -294,6 +308,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void errorHandlerWhenHandlerIsNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> this.builder.errorHandler(null))
 			.withMessageContaining("'errorHandler' must not be null");
@@ -366,12 +381,14 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void customizersWhenCustomizersAreNullShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> this.builder.customizers((RestTemplateCustomizer[]) null))
 			.withMessageContaining("'customizers' must not be null");
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void customizersCollectionWhenCustomizersAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.customizers((Set<RestTemplateCustomizer>) null))
@@ -405,6 +422,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void additionalCustomizersWhenCustomizersAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.additionalCustomizers((RestTemplateCustomizer[]) null))
@@ -412,6 +430,7 @@ class RestTemplateBuilderTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void additionalCustomizersCollectionWhenCustomizersAreNullShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> this.builder.additionalCustomizers((Set<RestTemplateCustomizer>) null))
@@ -486,8 +505,10 @@ class RestTemplateBuilderTests {
 	}
 
 	private ClientHttpRequest createRequest(RestTemplate template) {
-		return ReflectionTestUtils.invokeMethod(template, "createRequest", URI.create("http://localhost"),
-				HttpMethod.GET);
+		ClientHttpRequest request = ReflectionTestUtils.invokeMethod(template, "createRequest",
+				URI.create("http://localhost"), HttpMethod.GET);
+		assertThat(request).isNotNull();
+		return request;
 	}
 
 	static class RestTemplateSubclass extends RestTemplate {
diff --git a/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/RootUriTemplateHandlerTests.java b/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/RootUriTemplateHandlerTests.java
index ffc7b99c80d..9140f2e8c82 100644
--- a/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/RootUriTemplateHandlerTests.java
+++ b/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/RootUriTemplateHandlerTests.java
@@ -48,6 +48,7 @@ class RootUriTemplateHandlerTests {
 	private URI uri;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	public UriTemplateHandler delegate;
 
 	public UriTemplateHandler handler;
@@ -59,6 +60,7 @@ class RootUriTemplateHandlerTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWithNullRootUriShouldThrowException() {
 		assertThatIllegalArgumentException()
 			.isThrownBy(() -> new RootUriTemplateHandler((String) null, mock(UriTemplateHandler.class)))
@@ -66,6 +68,7 @@ class RootUriTemplateHandlerTests {
 	}
 
 	@Test
+	@SuppressWarnings("NullAway") // Test null check
 	void createWithNullHandlerShouldThrowException() {
 		assertThatIllegalArgumentException().isThrownBy(() -> new RootUriTemplateHandler("https://example.com", null))
 			.withMessageContaining("'handler' must not be null");
diff --git a/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/autoconfigure/AutoConfiguredRestClientSslTests.java b/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/autoconfigure/AutoConfiguredRestClientSslTests.java
index 79be8b78633..98c1ede6136 100644
--- a/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/autoconfigure/AutoConfiguredRestClientSslTests.java
+++ b/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/autoconfigure/AutoConfiguredRestClientSslTests.java
@@ -52,12 +52,15 @@ class AutoConfiguredRestClientSslTests {
 		.withConnectTimeout(Duration.ofSeconds(30));
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private SslBundles sslBundles;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ClientHttpRequestFactoryBuilder<ClientHttpRequestFactory> factoryBuilder;
 
 	@Mock
+	@SuppressWarnings("NullAway.Init")
 	private ClientHttpRequestFactory factory;
 
 	private AutoConfiguredRestClientSsl restClientSsl;
diff --git a/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/autoconfigure/service/HttpServiceClientAutoConfigurationTests.java b/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/autoconfigure/service/HttpServiceClientAutoConfigurationTests.java
index 8f3d8c0786c..c2556f8709c 100644
--- a/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/autoconfigure/service/HttpServiceClientAutoConfigurationTests.java
+++ b/module/spring-boot-restclient/src/test/java/org/springframework/boot/restclient/autoconfigure/service/HttpServiceClientAutoConfigurationTests.java
@@ -222,7 +222,9 @@ class HttpServiceClientAutoConfigurationTests {
 		}
 
 		MockRestServiceServer getMock(String name) {
-			return this.mocks.get(name);
+			MockRestServiceServer mock = this.mocks.get(name);
+			assertThat(mock).isNotNull();
+			return mock;
 		}
 
 	}