CAI: change language of output from oData service

Hi,
we have integrated an oData Service from our backend S/4 HANA system (POST: creating a purchase req).

Per default, the output from the system is a message in English. We have added two field to the request:
Accept-Language: DE
sap-language: DE

In the response, the message is still in English, but not in DE. Does anyone have an idea?

BR
Simon

**Update: I have found the reason for the problem: The destination configuration is overwriting my header --> EN instead of DE; A question for all BTP Connectivity experts: How can I prevent the BTP connectivity service from overwriting my header infomation in the POST?**