@Override
  public void postCompletedTruncateTableAction(ObserverContext<MasterCoprocessorEnvironment> c,
    TableName tableName) throws IOException {
    if (needHandleTableHdfsAcl(tableName, "truncateTable " + tableName)) {
      // 1. create tmp table directories
      hdfsAclHelper.createTableDirectories(tableName);
      // 2. Since the table directories is recreated, so add HDFS acls again
      Set<String> users = hdfsAclHelper.getUsersWithTableReadAction(tableName, false, false);
      hdfsAclHelper.addTableAcl(tableName, users, "truncate");
    }
  }
Provider for mapping principal names to Users
hbase-server/src/main/java/org/apache/hadoop/hbase/security/access/SnapshotScannerHDFSAclController.java