Ignore scoped proxy targets for @ControllerAdvice beans

Prior to this commit, methods in a @ControllerAdvice bean were
registered and invoked twice if the advice was a scoped bean (e.g.,
request or session scoped). In other words, both the proxy bean and the
target bean were wrapped in ControllerAdviceBean instances.

This commit fixes this bug by modifying the findAnnotatedBeans() method
in ControllerAdviceBean so that it filters out targets of scoped
proxies.

Closes gh-24017

spring-web/src/main/java/org/springframework/web/method/ControllerAdviceBean.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2019 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.
@@ -20,6 +20,7 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.stream.Collectors;
 
+import org.springframework.aop.scope.ScopedProxyUtils;
 import org.springframework.beans.factory.BeanFactory;
 import org.springframework.beans.factory.BeanFactoryUtils;
 import org.springframework.context.ApplicationContext;
@@ -42,6 +43,7 @@ import org.springframework.web.bind.annotation.ControllerAdvice;
  * @author Rossen Stoyanchev
  * @author Brian Clozel
  * @author Juergen Hoeller
+ * @author Sam Brannen
  * @since 3.2
  */
 public class ControllerAdviceBean implements Ordered {
@@ -187,6 +189,7 @@ public class ControllerAdviceBean implements Ordered {
 	 */
 	public static List<ControllerAdviceBean> findAnnotatedBeans(ApplicationContext context) {
 		return Arrays.stream(BeanFactoryUtils.beanNamesForTypeIncludingAncestors(context, Object.class))
+				.filter(name -> !ScopedProxyUtils.isScopedTarget(name))
 				.filter(name -> context.findAnnotationOnBean(name, ControllerAdvice.class) != null)
 				.map(name -> new ControllerAdviceBean(name, context))
 				.collect(Collectors.toList());