Make JCacheManager/JCache more reusable

I've been looking into adding a cache subsystem to WildFly for jsr-107 integration. WildFly will need to implement its own CachingProvider that supplies custom CacheManager implementations, but I'd like to reuse as much of Infinispan's JCache implementation as possible. There are at least 2 issues preventing me from doing this:

1. JCache's constructor accepts a JCacheManager, but doesn't require any special methods. The generic interface could be used instead - thus allowing WildFly to create a JCache using its own CacheManager.
2. WildFly will want to customize specific behavior of Infinispan's JCache implementation, which becomes difficult since JCache is a final class.