docs: public User getUser(String username) throws GitLabApiException {
          GitLabApiForm formData = createGitLabApiForm().withParam("username", username, true);
          Response response = get(Response.Status.OK, formData.asMap(), "users");
          List<User> users = response.readEntity(new GenericType<List<User>>() {});
          return (users.isEmpty() ? null : users.get(0));
      }