Hi,

thank you for this great library.

I implemented the request validator as described in the documentation, but I get this exception after executing the authenticate_client method:

Authenticate client must set the request.client.client_id attribute in authenticate_client.

https://github.com/idan/oauthlib/blob/master/oauthlib/oauth2/rfc6749/grant_types/authorization_code.py#L374

Is there a difference between request.client_id and request.client.client_id? I think the line of code should be

if not hasattr(request, 'client_id'):