[keycloak-dev] Realm cache

There's still some outstanding issues with the realm cache. It works, but can and should be improved for 1.8. One issue was that once the realm is updated any methods on clients, roles or groups returns the underlying adapter instead of the cache adapters. As a work around in 1.7 it now ejects all clients for a realm when it sees any changes. We have a few potential ways to solve this: a) try to always return cache adapters - I went down this road attacking it from a few different approaches, but was never successful as there was always something that didn't work b) only cache realms and have everything else hang off it - this is my preferred option for now. As long as updating clients requires invalidating the realm it seems a bit over the top to have separate caches for everything c) make the cache smarter - instead of invalidating a realm, make sure we add/remove the clients, etc.. We also need more automated testing around clustering. Late in 1.7 release process I identified that caches where invalidated when other nodes loaded things to it, so effectively the cache wasn't working at all in a cluster. Thoughts?