class UserGroupInformation {

  @InterfaceAudience.Private
  @InterfaceStability.Unstable
  @VisibleForTesting
  public synchronized static void setLoginUser(UserGroupInformation ugi) {
    // if this is to become stable, should probably logout the currently
    // logged in ugi if it's different
    loginUser = ugi;
  }

    UserGroupInformation(Subject subject);

}