Mixer plugin for Nukkit (Broken until rewrite comes out), Bukkit, Sponge and Forge
To build, run gradle shadowJar. You also have to add spigot-1.9.jar, spigot-1.9.4.jar, spigot-1.10.2.jar, spigot-1.11.2.jar and spigot-1.12.2.jar to the /libs folder.
The output is in the /build/jars folder.
You also have to add a gradle.properties file. Blank file
The first build might take a while due to Forge.
A precompiled jar is availible at releases