PAC not supported in Java 15

[StFS]

Java 15 has removed Nashorn (https://openjdk.java.net/jeps/372).

However, there is a standalone Nashorn project (https://mail.openjdk.java.net/pipermail/nashorn-dev/2020-October/007557.html) now. It should be possible to declare a dependency on that project to get everything working with Java 15.

[gschnepp]

This project is dead. Just take an active fork like https://github.com/akuhtz/proxy-vole