If group validation is enabled (with my fix for #125) then if the group is deleted, the user is still allowed in as the cache is not updated.

I think we should be playing very safe here and failing. This also applies for nested groups.

There is a log message:

 {"error":"GROUP_NOT_FOUND","level":"error","msg":"error updating fill cache","service":"sso-authenticator",...

Version: master with PR 275 and PR 280 applied