The Jandex 3.0.6 release currently included in EAP 8.0.x has a known issue when running on SE 21 (see [1]), so for EAP 8.0 to support SE 21 we'll need to move to a version with that addressed.

What version to move to requires discussion with the Jandex team, hence the 3.?.? in the initial version of this issue's title.

As part of my work on EAP7-2148 I created https://docs.google.com/spreadsheets/d/1JoMCbj0oCchSgLOcD80PnpA_63FYRMO4f8dvA9cwxxM/edit#gid=0, which is meant to track the level of testing of Java SE 21 for the key component of EAP 8.0.x. Researching the Jandex situation I asked lthon@redhat.com, and he told me about [1].

This is fixed in 3.1.2 or later but 8.0.x is on 3.0.6. It is not currently fixed in the 3.0.x series.

WildFly has been on 3.1.2 or later since early July 2023, only a couple weeks after we branched for EAP 8.0.x, so doing a minor version update is something we should at least consider. (Note that just yesterday WildFly Core main moved to 3.2.0, so which minor to use is also a question.)

[1] https://github.com/smallrye/jandex/issues/310