As discussed here, it may be the time to think about refactoring the Request and the Response classes to follow the php-fig standards.

You can see this interfaces here.

Message from @iltar:

Actually, I've been thinking of converting the current Request/Response objects to builders. Parameter converters etc are all working by setting values and the same goes for response listeners. By converting the ResponseBuilder and RequestBuilder into a "frozen" variant, it can also be compliant with PSR. This means that when modifying the request > builder but your action > PSR request. Same goes for the response, you can return a Response(Builder), which gets converted to a PSR Response if not already.