Support @Nested tests in MockServerContainerContextCustomizerFactory

Prior to this commit, MockServerContainerContextCustomizerFactory did
not find @WebAppConfiguration on an enclosing class and therefore
failed to create a MockServerContainerContextCustomizer for a @Nested
test class.

This commit addresses this by using TestContextAnnotationUtils to
determine if the test class is "annotated" with @WebAppConfiguration.

Closes gh-29037

spring-test/src/main/java/org/springframework/test/context/web/socket/MockServerContainerContextCustomizerFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2016 the original author or authors.
+ * Copyright 2002-2022 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,26 +19,25 @@ package org.springframework.test.context.web.socket;
 import java.util.List;
 
 import org.springframework.beans.BeanUtils;
-import org.springframework.core.annotation.AnnotatedElementUtils;
 import org.springframework.lang.Nullable;
 import org.springframework.test.context.ContextConfigurationAttributes;
 import org.springframework.test.context.ContextCustomizer;
 import org.springframework.test.context.ContextCustomizerFactory;
+import org.springframework.test.context.TestContextAnnotationUtils;
+import org.springframework.test.context.web.WebAppConfiguration;
 import org.springframework.util.ClassUtils;
 
 /**
  * {@link ContextCustomizerFactory} which creates a {@link MockServerContainerContextCustomizer}
- * if WebSocket support is present in the classpath and the test class is annotated
- * with {@code @WebAppConfiguration}.
+ * if WebSocket support is present in the classpath and the test class or one of
+ * its enclosing classes is annotated or meta-annotated with
+ * {@link WebAppConfiguration @WebAppConfiguration}.
  *
  * @author Sam Brannen
  * @since 4.3.1
  */
 class MockServerContainerContextCustomizerFactory implements ContextCustomizerFactory {
 
-	private static final String WEB_APP_CONFIGURATION_ANNOTATION_CLASS_NAME =
-			"org.springframework.test.context.web.WebAppConfiguration";
-
 	private static final String MOCK_SERVER_CONTAINER_CONTEXT_CUSTOMIZER_CLASS_NAME =
 			"org.springframework.test.context.web.socket.MockServerContainerContextCustomizer";
 
@@ -68,8 +67,7 @@ class MockServerContainerContextCustomizerFactory implements ContextCustomizerFa
 	}
 
 	private static boolean isAnnotatedWithWebAppConfiguration(Class<?> testClass) {
-		return (AnnotatedElementUtils.findMergedAnnotationAttributes(testClass,
-				WEB_APP_CONFIGURATION_ANNOTATION_CLASS_NAME, false, false) != null);
+		return TestContextAnnotationUtils.hasAnnotation(testClass, WebAppConfiguration.class);
 	}
 
 }