Google Documents List API version 3.0 - Google Apps — Google Developers
Warning: The deprecation period for Version 3 of the Google Documents List API is nearly at an end. On April 20, 2015, we will discontinue service for this API. This means that service calls to the API are no longer supported, and features implemented using this API will not function after April 20, 2015. You must migrate to the Drive API as soon as possible to avoid disruptions to your application.
全然知らなかったんですが、コレって常識ですか？
諸般の事情でなくなると無茶困るんですが、、、orz
