Spring, CrudRepository, как реализовать update action?

@Transactional
    @RequestMapping(method = RequestMethod.PUT, path = "/{id}")
    public @ResponseBody
    String update(@PathVariable(value = "id") String id,
                            @RequestParam(required = false) String login,
                            @RequestParam(required = false) String name,
                            @RequestParam(required = false) String password) {
        Optional<User> user = userRepository.findById(Long.valueOf(id));

        if (user.isPresent()){

            User u = user.get();

            if (login != null)
                u.setLogin(login);

            if (name != null)
                u.setUsername(name);

            if (password != null)
                u.setPassword(password);

            userRepository.save(u);
            return "{ status : success }";
        }

        return "{ status : error }";
    }

package spp.lab.reposository;

import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;
import spp.lab.models.User;

@Repository
public interface UserRepository extends CrudRepository<User, Long> {

}