why does EntityDataCachingConfig return the comparator through a supplier (to me returning null iff isVersioned() == false would be fine) while CollectionDataCachingConfig.getOwnerVersionComparator returns the comparator directly?

Well first, wrt "why can't the config object just return Comparator rather than both exposing `#isVersioned` and the Comparator?"... sure we can do that. In fact it was one of the questions I specifically asked you initially. So happy to change that one - I thought the same.

As for the rest, especially reference to a "delegator"... I have no idea what you are asking...

SharedSessionContractImplementor parameter is missing from StorageAccess methods. Infinispan uses that the retrieve TransactionCoordinator in query cache. Could you add that before the SPI goes final please?

Well first, usage of StorageAccess is optional - it is merely a simplified "underlying cache access" strategy for cache providers wanting to implement support through org.hibernate.cache.spi.support (as opposed to the more general org.hibernate.cache.spi package). But regardless, I don't think it hurts to add it there