[wtetzner]

But can't you continue to run older bytecode versions on newer JVMs? I think you can also specify the source version separately.

[samus]

Yes, you can. There is no need to recompile, unless you're interested in new language features.

Maintaining binary compatibility is a principal goal of the platform which continues to constrain design decisions for all future changes.

[doikor]

There are some actual removal of feature too (breaking backwards compatibility on purpose). But those come with deprecation warnings for years before the actual feature is removed. And even then quite often it is still possible to enable with some feature flag for a version or two.