@RequestMapping(value = "/update", method = RequestMethod.POST)
  public @ResponseBody UserDto update(
      @RequestParam String username,
      @RequestParam String firstName,
      @RequestParam String lastName,
      @RequestParam Integer role) {

    Role existingRole = new Role();
    existingRole.setRole(role);

    User existingUser = new User();
    existingUser.setUsername(username);
    existingUser.setFirstName(firstName);
    existingUser.setLastName(lastName);
    existingUser.setRole(existingRole);

    return UserMapper.map(service.update(existingUser));
  }