code: @Override
    protected void startUp() throws Exception {
      try {
        UserGroupInformation.setConfiguration(_hadoopConf);
        if (UserGroupInformation.isSecurityEnabled()) {
          UserGroupInformation.loginUserFromKeytab(_loginUser, _loginUserKeytabFile);
        }
      } catch (Throwable t) {
        log.error("Failed to start up HadoopKerberosKeytabAuthenticationPlugin", t);
        throw t;
      }
  
    }
docs: {@inheritDoc}