Get a list of all (automatically used) http headers


I want to integrate a REST Webservice in Xojo which uses a special authentication method.
The api provider wants a hash of the signed version of all http headers that we send.
Therefore I need to get all headers which Xojo generates automatically (“Accesspt-Encoding”, Cookies, User-Agent, etc) or remove them all.

Is there a way to do this?

Best regards