assaf/rack-oauth2-server — pull request #23 by gaku (2012-06-12 07:04:11+00:00)
Title: added missing json gem

Commented on the previously opened issue about missing require 'json'
https://github.com/assaf/rack-oauth2-server/issues/4#issuecomment-6264281

Here's an one-line patch to address the issue.