Ah...I commented on your issue in Jira, but didn't notice until I read this that your app is a Canvas app. That's *TOTALLY* different.
First, please note that the canvas sample app is no longer in GitHub. I removed it because it was demonstrating the wrong way of obtaining an access token using the ConnectController/OAuth2 connection flow. The correct way for FB Canvas apps, as you suggested in one of your comments, is to use the auth dialog and to obtain the token via the signed_request parameter.
This is not a bug in Spring Social itself. It is perhaps an unsupported (or perhaps not directly supported) feature in Spring Social, but not a bug in Spring Social. At very least it is a lack of a proper example for doing Spring Social with Facebook Canvas apps. It's funny that this *exact* topic has come up several times over the past couple of weeks. I guess it's a sign that I need to provide a correct example (which, is already in progress).
Spring Social Project Lead