The following solution triggers a GET request and converts the returned JSON response into User:

Jsonb jsonb = JsonbBuilder.create();
HttpClient client = HttpClient.newHttpClient();

HttpRequest requestGet = HttpRequest.newBuilder()
  .uri(URI.create("https://reqres.in/api/users/2"))
  .build();

HttpResponse<User> responseGet = client.send(
  requestGet, JsonBodyHandler.jsonBodyHandler(jsonb, User.class));

User user = responseGet.body();