HHH-15466 Compatibility with Jandex 3.0.0

[Ladicek]

The only change in Jandex 3.0.0 relevant to Hibernate ORM is that
Indexer.index() used to return ClassInfo, but now returns void.
This is a breaking change, but Jandex 3.0.0 has a synthetic bridge
method with the old signature for binary compatibility -- except
it always return null. Therefore, with this commit, Hibernate ORM
simply ignores the return value completely, which makes it compatible
with Jandex 3.0.0 at runtime, even though it is still compiled against
Jandex 2.4. The code is also source-compatible with Jandex 3.0.0 if
that is ever needed.

[Sanne]

Jandex 3.0.0 has a synthetic bridge method with the old signature for binary compatibility -- except it always return null.

Just curious, why would you add the method bridge if it's not actually useful towards achieving backwards compatibility?

[Ladicek]

It achieves binary compatibility, and that allows achieving backwardforward compatibility in a straightforward manner (this PR). Without that, it would be impossible e.g. for Hibernate to be compatible with both Jandex 2.x and 3.0 at the same time.

There's actually a lot of callers of Indexer.index() out there that outright ignore the return value -- those are compatible immediately.

[Sanne]

ah, ok right that makes sense. Thanks!