[keycloak-dev] Integration test: Verify url that was used in an adapter backchannel request

I currently work on KEYCLOAK-6073 (Support different URLs for front and back channel requests in adapters) and try to implement some kind of integration test, to verify that an adapter actual use its configured url for backchannel requests. When I understand the existing integration tests correct, it should be relative easy to trigger most of the actions that execute backchannel requests (code-to-token, logout, etc.) with an adapter test (AbstractExampleAdapterTest, AbstractServletsAdapterTest). But I don't see a straight forward way how to verify the url that was actual used by the adapter (in the deployed example or servlet). Not sure if I am on the right track, so any thoughts on how to approach this are appreciated. :) Thanks Luca