docs: public void postRegistration(String username, String password, String email, String fullname) {
          ClientResource resource = new ClientResource(Route.REGISTER.url());
  
          Form form = new Form();
          form.add("username", username);
          form.add("password_1", password);
          form.add("password_2", password);
          form.add("email", email);
          form.add("fullname", fullname);
  
          resource.post(form);
      }