public void update(User user) throws NotFoundException, ServerException, ConflictException {
  requireNonNull(user,"Required non-null user");
  userDao.update(new UserImpl(user));
}

public void update ( User user ) throws NotFoundException , ServerException , ConflictException { requireNonNull ( user , "Required non-null user" ) ; userDao . update ( new UserImpl ( user ) ) ; }
updates user by replacing an existing user entity with a new one .
