Currently in the process of trying to move over to use OAuth2 from of OAuth1 2LO (2 Legged OAuth). At first it looked like we would not be able to make the move as we rely heavily on 2LO and almost all of the product APIs (with the exception of Drive) have this message in their docs:

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> If your application has certain unusual authorization requirements, such as logging in at the same time as requesting data access (hybrid) or domain-wide delegation of authority (2LO), then you cannot currently use OAuth 2.0 tokens. In such cases, you must instead use OAuth 1.0 tokens and an API key.
>  - <https://developers.google.com/google-apps/calendar/auth>
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Some of the newer APIs (like the Admin SDK APIs) also have the same message. 

While looking at the Drive Delegation Document: <https://developers.google.com/drive/delegation>, it explicitly talks about using domain-wide delegation for calendar:

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> In the One or More API Scopes field enter the list of scopes that your application should be granted access to (see image below). For example if you need domain-wide access to the Google Drive API and the Google Calendar API enter: <https://www.googleapis.com/auth/drive>, <https://www.googleapis.com/auth/calendar>
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This seems to directly contradict the calendar auth doc. Does anyone know which other APIs support Domain-Wide Delegation?