Support Java 21 sequenced collections

[beikov]

Since Jakarta EE 11 bumps the Java requirement to 21, Jakarta Persistence should IMO do so as well. If time permits, it should IMO also add support for the new sequenced collection interfaces:

• SequencedCollection
• SequencedSet
• SequencedMap

These types should be supported collection types which are useful when using @OrderBy("some_column").

[lukasj]

Since Jakarta EE 11 bumps the Java requirement to 21

this may be not true in the end eventually, there is a wish to stick with 17 and it is likely there will be some voting about it in the near future.

In any case, from the persistence spec - and my - point of view:

• in 3.2 - we want to allow vendors to support SE 17 without the need for multi-release jar overhead
• in 3.2.NEXT - bump to SE 21+ and add explicit support for SequencedCollections

WDYT?

[beikov]

Sounds good to me. I just wanted to propose an actually useful feature that requires Java 21 if Jakarta Persistence were to bump to that version.