public SystemUserPropertyDTO add(AuthenticationDTO auth, SystemUserPropertyDTO dto)
     throws ApplicationException {
   authenticate(auth);
   if (dto == null) throwException(1);
   SystemUserProperty entity = session.get(dto.getId());
   if (entity != null) throwException(2);
   entity = SystemUserPropertyUtil.createEntity(dto);
   return SystemUserPropertyUtil.copy(session.add(entity));
 }