There's an official specification for what and how a program that claims to be a JVM implementation should operate given Java bytecode. So someone writing a lan

There's an official specification for what and how a program that claims to be a JVM implementation should operate given Java bytecode. So someone writing a language that compiles to Java bytecode would typically either target the specification (and test on as many implementations as they felt necessary), or target a specific implementation like HotSpot and ignore the rest.