Correct me if I'm wrong, but Rust editions are a source code-level feature. So given you have the source code of newer and older rust code, you can compile them together.
That's materially distinct from Java's model of basically dynamic loading already compiled class files. Though class files do have "editions", and there are extra code to deal with different versions. But still, it should be possible to e.g. send a new value class to an old library's class that has never heard of them, and that should just work.
The important thing is that Rust editions affect semantics and name resolution. In such an analogy, JVM bytecode is the equivalent of Rust code - various semantics are baked in, but stuff like name resolution isn't (at least not completely).