For now, we provide content negotiation with HTTP headers, in a not very professional way, but it works. At the meeting Meeting 2020-05-19, it was ask what we provide and if not a URL pattern negotiation would be better/nicer. Christoph stated, we should stick to one negotiation type, although it is possible to use both, it would be not clear for an application or user.
It is up for discussion.
(very short and simple explaination)