Great initiative!
For the Hibernate Search use case, it would be nice if this could:

• check first for already managed entities
• second check for 2' level cache stored entities [Optionally? Maybe this should be an opt-in flag]
• load the remaining entities only via batching

Ultimately the returned result should have them all, so to fill in the entities from these different sources, but maintaining the requested order as defined by the list of keys.