Hello,
after spending some time on google i didn't find a helping thread.. so i'll give it a try at the SCN 
We've developed a gateway service to create leaverequests.
The included check returns warning messages as "leave request is in workfree time" - for example for a weekend.
The LR will still be persisted - so no exceptions.
But i want to return these messages to the gatewayservice/frontend.
I found a thread that helped me a little, but i'm not quite satisfied yet.
=> Success/Error/Info Message in return of Odata Service response from ECC
The message will only be returned if i raise an exception.
But i don't want a 400 Bad Request.
The GW Component is updated to SP8 as suggested by Ralf Handl.
Did i do something wrong? Is it even possible to include messages in the return-body?
I tried the example code from the thread linked above.
Thanks for advice!
Greetings,
Pascal