Handle scoped proxy properly in MBeanExporter

Previously, if a bean has a scoped proxy and is annotated to be exposed
to the JMX domain, both the scoped proxy and the target instance were
exposed in the JMX domain, resulting in a duplicate entries. Worse, if
such bean defines an explicit name, the application wouldn't start
because of a name conflict.

This commit deals explicitely with scoped proxy and make sure to only
expose the relevant bean.

Issue: SPR-12529

spring-aop/src/main/java/org/springframework/aop/scope/ScopedProxyUtils.java

@@ -97,4 +97,12 @@ public abstract class ScopedProxyUtils {
 		return TARGET_NAME_PREFIX + originalBeanName;
 	}
 
+	/**
+	 * Specify if the {@code beanName} is the name of a bean that references the target
+	 * bean within a scoped proxy.
+	 */
+	public static boolean isScopedTarget(String beanName) {
+		return beanName.startsWith(TARGET_NAME_PREFIX);
+	}
+
 }