[cowl]

How does it go against the HTTP Spec. The HEAD method could be autoregistered for all handlers of GET Requests and library makes sure no body is sent (Basically it's a autoregistered middleware that wraps the get handler and overwrites the reponse writer with an empty body.)

Arguably this is more correct that letting the users declare a separate Handler that can neither guarantee the same headers as the the GET Handler not guarantee that the body is not sent the response.