We currently use OpenID authentication for the applications we develop. This is going to be deprecated in April 2015, and we have to migrate to OpenID Connect/Google Plus Sign-In before.
However, right now we take advantage of the seamless authentication provided by OpenID and Google Apps Console. That is to say, if we create an app which uses OpenID for authentication, and then we install this app through the Marketplace or Google Apps Console, the user is not prompted for a confirmation or warning screen during the OpenID authentication.
This is because, during the Marketplace/Google Apps Console app installation, the admins have indicated that they trusted the OpenID realm of this application.
Will this behavior still be effective with G+ SignIn and OpenID connect ? Is there anything specific to do to enforce this behavior ?
I've finally found the solution and wrote a blog post about the whole process.