增加认证相关注释

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ha/ZKFailoverController.java

@@ -372,6 +372,7 @@ private void initZK() throws HadoopIllegalArgumentException, IOException,
     int maxRetryNum = conf.getInt(
         CommonConfigurationKeys.HA_FC_ELECTOR_ZK_OP_RETRIES_KEY,
         CommonConfigurationKeys.HA_FC_ELECTOR_ZK_OP_RETRIES_DEFAULT);
+    // 初始化主备选举对象。
     elector = new ActiveStandbyElector(zkQuorum,
         zkTimeout, getParentZnode(), zkAcls, zkAuths,
         new ElectorCallbacks(), maxRetryNum);