code: private UserGroupInformation getCurrentUGI(HiveConf opConfig) throws HiveSQLException {
      try {
        return Utils.getUGI();
      } catch (Exception e) {
        throw new HiveSQLException("Unable to get current user", e);
      }
    }
docs: Returns the current UGI on the stack
  @param opConfig
  @return UserGroupInformation
  @throws HiveSQLException