Response

You're able to return anything you want from your API method: Strings, Lists, Maps, and even your own objects. But returning these kind of objects doesn't permit you to change the status code of your response. It's only possible when you return a Response object as follows:

@API(path: 'beers')
class BeerAPI {

    @GET()
    Response hi() {
        return new Response()
               ..statusCode = 200
               ..body = "Hi!";
    }

    @GET(':id')
    Response get() {
        return new Response()
               ..statusCode = 200
               ..entity = new MyEntity();
    }
}