打印zk通知代码，方便查找问题

matrix-gracefulshutdown/src/main/java/com/secoo/mall/gracefulshutdown/component/hook/DubboCustomerShutDownHook.java

@@ -179,7 +179,7 @@ public class DubboCustomerShutDownHook extends AbstractShutDown implements Obser
 
     @Override
     public void update(Observable o, Object arg) {
-        logger.info("result:" + arg);
+        logger.info(" zk notice result:" + arg);
         synchronized (checkContent) {
             check = true;
             checkContent.put((String) arg, false);