Approximately none. Which is why I would be fine with javac generating a synthetic public static void main(string[] args) that forwards to it when the pattern

Approximately none. Which is why I would be fine with javac generating a synthetic public static void main(string[] args) that forwards to it when the pattern is encountered. In this setup the generated classes/jars work fine without extra flags to java and even work on older jvm installations if you pass the right flags to javac at build time. I really struggle to come up with a reason to implement this as a change to java vm over just javac.