Create the /tmp directory as <i>hdfs</i> and /tmp/test as <i>sink</i> and
   * return the UGI for <i>sink</i>.
Create the /tmp directory as <i>hdfs</i> and /tmp/test as <i>sink</i> and
   * return the UGI for <i>sink</i>. | TestRollingFileSystemSinkWithSecureHdfs.java