I'm using appengine/Java.
I'm aware Google dropped its support as OpenId Provider. Thefore, I migrated to OpenID connect for my Sign-in with Google,
As it was stated that App Engine would still support third party OpenId providers, I still use OpenId for my sign-in with AOL and Yahoo.
Now I get in my logs the following warning:
com.google.appengine.api.users.UserServiceImpl createLoginURL: Open ID 2.0 support in the App Engine Users service is deprecated and will soon be removed. Please see https://cloud.google.com/appengine/docs/deprecations/open_id for details.
which points to https://cloud.google.com/appengine/docs/deprecations/open_id.
However this page is not clear about whether it's just about Google not being OpenId provider anymore, or that appengine will not support the OpenId feature anymore, also for providers that still support OpenId, like AOL and Yahoo.
If this is the case, which I fear: how to migrate these accounts?
Yes, OpenID 2.0 Relying Party support for logging in with OpenID 2.0 accounts in to App Engine will be turned off as stated on that page:
OpenID 2.0 is an alpha feature of the Users API that allows non-Google accounts to login to the App Engine Users API
This is in addition to the Google Apps migration from OpenID 2.0 to OpenID Connect.
You will have to migrate accounts manually to other protocols as done in: Java example how to login with Facebook account on GAE using OAuth