Merge pull request #1860 from griswold1991/master

Fix ConcurrentModificationException while EventDispatcher.run after '…

spring-cloud-alibaba-starters/spring-cloud-starter-dubbo/src/main/java/com/alibaba/cloud/dubbo/metadata/repository/DubboServiceMetadataRepository.java

@@ -237,9 +237,6 @@ public class DubboServiceMetadataRepository
 		dispatchEvent(new SubscribedServicesChangedEvent(this, oldSubscribedServices,
 				newSubscribedServices));
 
-		// clear old one, help GC
-		oldSubscribedServices.clear();
-
 		return newSubscribedServices.stream();
 	}