Investigate JEP 401: Value Classes and Objects (Preview)

[He-Pin]

Enhance the Java Platform with value objects: class instances that have only final fields and lack object identity.

refs: https://openjdk.org/jeps/401

https://kotlinlang.org/docs/inline-classes.html https://github.com/Kotlin/KEEP/blob/master/notes/value-classes.md https://github.com/scala-native/improvement-proposals/pull/1