Change headers for original request in a authorization template out of process adapter?

So I have an out of process mixer adapter that handles authorization using an external service. The adapter works fine based on the out of process adapter walk-through but I need to set an additional header to the original request based on the response from external service.

Currently there is no HandleAuthorizationResponse in the proto

Is there any way to do this? I did come across this Route directive adapter guide that uses a custom template and uses responseHeaderOperations.
Is it possible to replicate this using existing authorization template?