Use dynamically resolved Java version when creating Gradle projects

[gsmet]

Also add tests for Java 21.
Fixes #37047

[ia3andy]

LGTM

[ia3andy]

But is it ok to have this: https://github.com/quarkusio/quarkus/blob/main/independent-projects/tools/base-codestarts/src/main/resources/codestarts/quarkus/tooling/dockerfiles/base/Dockerfile-layout.include.qute#L80

[gsmet]

For now, I don't think we have Java 21 images unfortunately but @cescoffier should know more.

[ia3andy]

For now, I don't think we have Java 21 images unfortunately but @cescoffier should know more.

That's why I suggested not to allow Java 21 yet

[ia3andy]

Maybe we could find a solution and put a warning on something in the dockerfiles?

[cescoffier]

We are waiting for the image. I heard that should be ready in November.

[quarkus-bot]

✔️ The latest workflow run for the pull request has completed successfully.

It should be safe to merge provided you have a look at the other checks in the summary.

[gsmet]

@ia3andy feel free to do something about it but we would have to revert very soon. We have allowed 21 in Maven for a while and we haven't heard any complaints (yet...). I agree the situation is not perfect but people are eager to use 21 and forbidding them to do it looks like a bad bet to me - even if some pieces are unfortunately missing.

I will merge this one, feel free to follow up.