if (modifier == null) {
if (this.modifier == null) {
  public Subject getModifySubject()     throws SubjectNotFoundException  {    if (modifier == null) {      Member m = this.getModifier_id();      if (m == null) {        throw new SubjectNotFoundException(          "group has not been modified"        );      }      modifier = m.getSubject();    }    return modifier;   } // public Subject getModifySubject()