In this weblog system, "nickname" and "email" required to IdP. This is from a behaviour of the original RestfulOpenIDAuthentication plugin. (I think that it is expecting the myopenid.com as default IdP and it has them as mandatory parameters.)

If you are using other IdP, it might have neither "nicknames" nor "email". In that case, you need to fill the lacking parameters and to retry.

Obviously, that was a big barrier for users. So I have changed this system so that can make IdPs free from required parameters and make a chance to add the lacking informations immediately.

I consider that every IdCs require such the mechanism due to the architecture of OpenID.