Provide a builder class that allows passing in of SPI instances, rather than doing lookup. This allows for much easier integration, as context from the app server bootstrap can be easily passed in.
We would still want to offer a wrapper around this for Java SE users that would expose a create a CacheManager easily. This factory would want to use a CacheManagerBuilder internally to create the cache, but offer a simplified API. You would want to expose the Builder from the factory as well, offering a sensible set of defaults for SE.
This would break backwards compatibility, as doing new EmbeddedCacheManager etc. would no longer be possible.