@RequestMapping(path = "/user/{username}", method = GET)
  @PreAuthorize("hasRole('ADMIN')")
  public ResponseEntity<User> getUser(@PathVariable("username") String username) {
    Optional<User> user = securityService.getUserByUsername(username);

    return user.isPresent()
        ? new ResponseEntity<User>(user.get(), HttpStatus.OK)
        : new ResponseEntity<>(HttpStatus.NOT_FOUND);
  }