void unregisterDagDir(String pathString, String appId, int dagIdentifier) {
    // TODO Implement to remove all watches for the specified pathString and it's sub-tree
  }
Register a base dir for an application
@param pathString the full path including jobId, user - /${local.dir}/appCache/${appId}/userCache/${user}
@param appId the appId
@param user the user
@param expiry when to expire the watch - in ms
@throws IOException
llap-server/src/java/org/apache/hadoop/hive/llap/shufflehandler/DirWatcher.java