So some JITs can be given hints that certain objects are just values, and things like identity will never be used, and thus they can be boxed and unboxed as nee

So some JITs can be given hints that certain objects are just values, and things like identity will never be used, and thus they can be boxed and unboxed as needed, but this is a pretty low level mechanism, and it’s probably not the thing to expose to most users as it can be brittle both in terms of safety and performance. There are a few other internal annotations in the JDK which are useful in the same way but aren’t exposed for similar reasons. Adding value types to a VM or language means exposing that sort of feature in a way that can be used by programmers and provides the sort of safety guarantees they are used to.