How to define JWT token mode for client_credentials flow in node oidc-provider

Question

I try to use the https://github.com/panva/node-oidc-provider for our OAuth implementation.

There we have also some services that have to use client_credentials flows. Currently we are getting an opaque Access Token but we need this as a JWT Token.

In the past > 7.x it was possible if define

{
  formats: {
    ClientCredentials: 'jwt',
    AccessToken: 'jwt',
  }
}

But this was removed with the major version 7.x

What do we have to define to receive also for the client_credentials flow an jwt token as well?