access req.user in server.authorization() validation

I am trying the following..
server.authorization( function(clientID, redirectURI, done) {
// access req.user here
}
I want to check to make sure the clientID is really accessible by the user, but looking at the code, there doesn't seem to be a way. Or am I doing something really wrong?

Start at the server.authorization() entry point and trace how its validation callback is invoked. Check the repository’s request-handling conventions to determine how the current user could be available for clientID validation. Done means the callback behavior supports checking the client against the user, with coverage for the authorization flow.

Written by the indexing model from the issue text.