Logout not working

[TanVD]

We use OAuth 2.0 Authentication-Code flow to authenticate users on service. For now it implements logging in, but will not work for logout, because after logging out from service you will be redirected to Authentication Service where you have already authenticated and then will be redirected back to service and will be authenticated again with OAuth 2.0. We need to implement full logout flow - first logout from Authentication Service, then from service.