OIC - REST Invoke - custom headers starting with x- are not sent

Hello,

i have an integration invoking an external system's REST API. This API requires a set of headers which name starts with "x-", like x-jws-signature.

It seems that these header are not sent, even if they are correctly mapped. In the activity stream i see the values mapped in the mapper action, but not in the sent headers in the Invoke action.

I didn't find much on Oracle documentation.

Is there any way to send this kind of attributes?

Thanks.