Note missing on expunge command description for encrypted zones

expunge command is supported for both encrypted and non-encrypted hdfs paths . This operation initially needs to discover/list all such paths. Listing/Discovering encrypted zone paths is only supported by superuser and expunge command misleads us by printing below message though its a warning . We could add some message in the expunge command description saying that the command supports encrypted zone paths only when run as superuser and it will continue listing and performing the operation for all non encrypted hdfs paths.

19/06/25 08:30:13 WARN hdfs.DFSClient: Cannot get all encrypted trash roots
org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.security.AccessControlException): Access denied for user ambari-qa. Superuser privilege is required
at org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkSuperuserPrivilege(FSPermissionChecker.java:130)