How to observe credential in AuthenticationInterceptor from Alamofire

I'm using AuthenticationInterceptor with a custom Authenticator to handle the token refresh.

Since we are migrating from an old network stack to Alamofire, I need to keep track of the credential property in AuthenticationInterceptor to feed that into the old network stack.

Is there anyway to observe the change of credential .

Unfortunately, AuthenticationInterceptor is not open for subclassing.