code: @POST
    @PermitAll
    public Response signup(DUser user, @Context UriInfo uriInfo) {
  
      LOGGER.debug("Sign up user {}", user.getUsername());
  
      if (!shouldUseEmailAsUsername) {
        checkUsernameFormat(user.getUsername());
      }
      checkPasswordFormat(user.getPassword());
      checkEmailFormat(user.getEmail());
  
      user = userService.signup(user);
  
      // Location of created user resource
      UriBuilder uriBuilder = uriInfo.getAbsolutePathBuilder()
          .path(user.getId().toString());
  
      return Response.created(uriBuilder.build())
          .entity(user.getId())
          .build();
    }
docs: Sign up a new user.
  
  @param user    user info
  @param uriInfo injected
  @return http 201 if successfully created
  The URI of the created user will be stated in the Location header