BeanFactoryAdvisorRetrievalHelper avoids synchronization for name cache

Issue: SPR-16570

spring-aop/src/main/java/org/springframework/aop/framework/autoproxy/BeanFactoryAdvisorRetrievalHelper.java

@@ -45,7 +45,7 @@ public class BeanFactoryAdvisorRetrievalHelper {
 	private final ConfigurableListableBeanFactory beanFactory;
 
 	@Nullable
-	private String[] cachedAdvisorBeanNames;
+	private volatile String[] cachedAdvisorBeanNames;
 
 
 	/**
@@ -66,16 +66,13 @@ public class BeanFactoryAdvisorRetrievalHelper {
 	 */
 	public List<Advisor> findAdvisorBeans() {
 		// Determine list of advisor bean names, if not cached already.
-		String[] advisorNames = null;
-		synchronized (this) {
-			advisorNames = this.cachedAdvisorBeanNames;
-			if (advisorNames == null) {
-				// Do not initialize FactoryBeans here: We need to leave all regular beans
-				// uninitialized to let the auto-proxy creator apply to them!
-				advisorNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
-						this.beanFactory, Advisor.class, true, false);
-				this.cachedAdvisorBeanNames = advisorNames;
-			}
+		String[] advisorNames = this.cachedAdvisorBeanNames;
+		if (advisorNames == null) {
+			// Do not initialize FactoryBeans here: We need to leave all regular beans
+			// uninitialized to let the auto-proxy creator apply to them!
+			advisorNames = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(
+					this.beanFactory, Advisor.class, true, false);
+			this.cachedAdvisorBeanNames = advisorNames;
 		}
 		if (advisorNames.length == 0) {
 			return new ArrayList<>();