docs: public Request<UserInfo> userInfo(String accessToken) {
          Asserts.assertNotNull(accessToken, "access token");
  
          String url = baseUrl
                  .newBuilder()
                  .addPathSegment("userinfo")
                  .build()
                  .toString();
          CustomRequest<UserInfo> request = new CustomRequest<>(client, url, "GET", new TypeReference<UserInfo>() {
          });
          request.addHeader("Authorization", "Bearer " + accessToken);
          return request;
      }