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

See gh-47263

module/spring-boot-webclient/build.gradle

@@ -44,3 +44,7 @@ dependencies {
 
 	testRuntimeOnly("ch.qos.logback:logback-classic")
 }
+
+tasks.named("compileTestJava") {
+	options.nullability.checking = "tests"
+}

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

@@ -126,6 +126,7 @@ class ReactiveHttpServiceClientAutoConfigurationTests {
 		then(builder).should().clientConnector(connectorCaptor.capture());
 		ClientHttpConnector client = connectorCaptor.getValue();
 		HttpClient httpClient = (HttpClient) ReflectionTestUtils.getField(client, "httpClient");
+		assertThat(httpClient).isNotNull();
 		assertThat(httpClient.connectTimeout()).contains(expectedReadTimeout);
 	}