[ISSUE alibaba#11880]Fixed the issue of duplicate notifications of co…

…nfiguration changes. (alibaba#11881)

client/src/main/java/com/alibaba/nacos/client/config/impl/ClientWorker.java

@@ -693,7 +693,8 @@ private void initRpcClientHandler(final RpcClient rpcClientInner) {
              */
             rpcClientInner.registerServerRequestHandler((request, connection) -> {
                 if (request instanceof ConfigChangeNotifyRequest) {
-                    handleConfigChangeNotifyRequest((ConfigChangeNotifyRequest) request, rpcClientInner.getName());
+                    return handleConfigChangeNotifyRequest((ConfigChangeNotifyRequest) request,
+                            rpcClientInner.getName());
                 }
                 return null;
             });