Update: The following advice no longer applies starting Minecraft 1.16, because developers can now use the “libraries” feature of their plugin.yml to include Nashorn library automatically. If you use our plugins such as ChatControl, Boss, CoreArena, Confiscate and Winter, this is done for you automatically. The advice below however, still applies if you decide to run Java 15+ on Minecraft 1.15 or older.
How to use NashornPlus:
A) If you’re using one of our plugins like ChatControl Red, Boss, CoreArena or others, all you need to do is install NashornPlus as a plugin and that’s it.
C) If you’re developing your plugin without Foundation, install NashornPlus as a separate plugin, then import Nashorn as a Maven or Gradle dependency (do not include it in the final jar). You can use this code snippet as an example of importing and using it.
Download NashornPlus from here: