@Transactional
 @Override
 public void delete(UserDto userDto) {
   if (userDto == null) {
     throw new NullPointerException();
   }
   User user = userConverter.userDtoToEntity(userDto);
   UserRole userRole = userRoleDao.findByUser(user);
   userRoleDao.delete(userRole);
   userDao.delete(user);
 }