It is impossible to change the output (or input) of rest services build with a Message Definition since we cannot change the "External (single) name". Also the adding of "s" is not always correct. It would be nice to be able to change this manually.
https://docs.mendix.com/refguide/message-definition
Thats is exactly what I wanted, interesting that I didn't try that, I guess it could be added to the documentation though. Thank you!
Can you explain a bit more? If you see an External Name or an External Single Item Name that you don't like, you can click it and change it, right?