Support for content type

[nbish11]

What are your thoughts about adding support for content negotiation in the actions?

In the action, using content negotiation methods:

final class GetPhoto
{
    public function html(int $id)
    {
        return new HtmlResponse($this->domain->findById($id));
    }
    public function json(int $id)
    {
        return new JsonResponse($this->domain->findById($id));
    }
}

or using an accepts method:

final class GetPhoto
{
    public function accepts()
    {
        return ['text/html', 'application/json'];
    }
    public function __invoke(int $id)
    {
        // The response is built based off the request format
        return $this->responder->__invoke($this->request, $this->domain->findById($id));
    }
}

The script for both scenarios above:

$matched = $autoRoute->route($request->method, $request->pathInfo, $request->contentType);
$matched->format = /* 'application/json' or 'text/html' */;

// if found for separate content negotiation methods
$matched->method = /* json() or html() */;

// or if found for one single method
$matched->method = /* __invoke() */;

// if not found
$matched->error = /* AutoRoute\Exception\NotAcceptable */;

Personally, I like the first method, as it's simpler to understand and allows more flexibility. However, from my understanding of the ADR pattern, its the responsibility of the Responder to build and return the response as either HTML, JSON, XML, etc. Maybe, the library can support both methods?