Hi,
already discovered this possibility. It works, but only for content-type JSON and with the concern that clients have to be modified to include the parameter ‘jsonFormat=…’ or the need to change the parameter globally via ‘watt.server.http.jsonFormat’ - and that is a NOGO for us.
So no real solution for me 
In the meanwhile i discovered the possibility of intercepting HTTP Requests globally via watt.server.http.interceptor. There i can access the raw bytes and i think it will be possible to transfer the data into flowservices.
Thank you.