Very clear advice to user when using Opaque Access Token that this will not work anymore beacuse of breaking changes

[dniel]

In the new version its mandatory to use JWT Access Token to be able to verify that the access token is valid and has not expired. This can only be done if the Access Token is in JWT format. Users that try to use the application with Opaque Access Token need to see a error message that very clearly describes this and what to do.