How to use forwarded AuthResponseHeaders as customResponseHeaders

Traefik Traefik v2
1

Hello!

I'm trying to add a cookie to the browser. So I'm using and auth service that creates a header (Set-Cookie) and sends it to the services inside the application, like this:

        jwtAuthentication:
            forwardAuth:
                address: "some/url/that/works"
                trustForwardHeader: true
                authResponseHeaders:
                    - "Set-Cookie"

I checked and the Set-Cookie header is sent to the service correctly.
The thing is that I want to add the same header as it is to the response without having to go inside the service and add the request header to the response headers, but I haven't found a clear answer to that:

        serviceAudience:
            headers:
                customRequestHeaders:
                    X-Audience: "some-x-audience"
                customResponseHeaders:
                    Set-Cookie: 'I don't know what to put here'

I know that if I add the Set-Cookie to the customResponseHeaders it will set a cookie on the browser with whichever value I provide, but I want the value from the forwarded auth service headers.

I tried a couple of solutions that didn't work out such as:

              customResponseHeaders:
                    Set-Cookie: Set-Cookie
              customResponseHeaders:
                    Set-Cookie: true
              customResponseHeaders:
                    Set-Cookie: Headers('set-cookie')