Can apps on Google Marketplace use Service Account authentication for Spreadsheet API and Calendar Resource API?

Question

What we want to do is to use Spreadsheet API and Calendar Resource API and to access to the API with 2-legged OAuth.
(Most likely, Service Account Authentication method in OAuth 2.0 is similar method. <2LO

To use these API, we tried Service Account Authentication method and successed in it.
However, the way of authentication with Service Account is not on the documents below. As for Spreasheet API, it should be used with OAuth 1.0 if implementing 2-legged OAuth. In terms of Calendar API, it should be used with 3-legged OAuth.

The success of retrieving data with Service Account is good for us and we ant to go on with it. But since the document doesn't tell us the way, we are confused if this is correct way. Can you tell me the way is whether formal admitted way by Google?

Spreadsheet API:
https://developers.google.com/google-apps/spreadsheets/?hl=ja#about_authorization_protocols

Calendar Resource API:
https://developers.google.com/admin-sdk/calendar-resource/auth

Thanks,

Answer 1

All Google APIs now support OAuth2, including service accounts. The documentation for these APIs hasn't been updated to reflect the change, but it should work correctly.