How to add audience form field on AccessTokenFetcher

[0xthc]

Hello there !
I'm struggling to understand what would be the best way to add the audience form field from auth0 on the AccessTokenFetcher.
From what I understand auth0 sends back an opaque token by default unless you provide an audience parameter to the token endpoint (cf https://community.auth0.com/t/why-is-my-access-token-not-a-jwt-opaque-token/31028)
If I'm correct this parameter should be added in the AccesTokenFetcher fetch method but as the requestForm is implemented as https://github.com/http4k/http4k/blob/master/http4k-security/oauth/src/main/kotlin/org/http4k/security/OAuthWebForms.kt#L15-L24 I'm not sure if it is possible to add the parameter without rewriting the whole thing.
The workaround would be to hit the /userinfo endpoint with the opaque token but I was wondering if these kind of settings would belong into this library or if it is out of scope.
https://github.com/http4k/http4k/blob/master/http4k-security/oauth/src/main/kotlin/org/http4k/security/AccessTokenFetcher.kt#L34-L37

In any way thanks for the time and thanks for the awesome work it really is a pleasure working with http4k