Add nullability annotations to tests in module/spring-boot-webclient-test

See gh-47263

module/spring-boot-webclient-test/build.gradle

@@ -40,3 +40,7 @@ dependencies {
 
 	testRuntimeOnly("ch.qos.logback:logback-classic")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}

module/spring-boot-webclient-test/src/test/java/org/springframework/boot/webclient/test/autoconfigure/AnotherExampleWebClientService.java

@@ -16,9 +16,14 @@
 
 package org.springframework.boot.webclient.test.autoconfigure;
 
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.http.ResponseEntity;
 import org.springframework.stereotype.Service;
 import org.springframework.web.reactive.function.client.WebClient;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 /**
  * A second example web client used with {@link WebClientTest @WebClientTest} tests.
  *
@@ -40,8 +45,10 @@ public class AnotherExampleWebClientService {
 		return this.builder;
 	}
 
-	public String test() {
-		return this.webClient.get().uri("/test").retrieve().toEntity(String.class).block().getBody();
+	public @Nullable String test() {
+		ResponseEntity<String> response = this.webClient.get().uri("/test").retrieve().toEntity(String.class).block();
+		assertThat(response).isNotNull();
+		return response.getBody();
 	}
 
 }

module/spring-boot-webclient-test/src/test/java/org/springframework/boot/webclient/test/autoconfigure/ExampleWebClientService.java

@@ -16,9 +16,14 @@
 
 package org.springframework.boot.webclient.test.autoconfigure;
 
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.http.ResponseEntity;
 import org.springframework.stereotype.Service;
 import org.springframework.web.reactive.function.client.WebClient;
 
+import static org.assertj.core.api.Assertions.assertThat;
+
 /**
  * Example web client using {@code WebClient} with {@link WebClientTest @WebClientTest}
  * tests.
@@ -41,8 +46,10 @@ public class ExampleWebClientService {
 		return this.builder;
 	}
 
-	public String test() {
-		return this.webClient.get().uri("/test").retrieve().toEntity(String.class).block().getBody();
+	public @Nullable String test() {
+		ResponseEntity<String> response = this.webClient.get().uri("/test").retrieve().toEntity(String.class).block();
+		assertThat(response).isNotNull();
+		return response.getBody();
 	}
 
 	public void testPostWithBody(String body) {