如何在goauth2中使用appengine / urlfetch包？

The goauth2 package has an example use. But on app engine, the normal http.Client isn't available. How do I use the app engine urlfetch package with goauth2?

You must add a Transport parameter to the first line of the callback:

t := &oauth.Transport{
    Config:    oauth_conf,
    Transport: &urlfetch.Transport{Context: c},
}