Java "Scripting"

Simple example on how this method of writing addons work.

CustomAddon.java

@name("Custom Addon")
@author("Example Author")
@description("A custom addon")

// this makes the player float while also spoofing it's ground state
// also print the client's username in chat
public void onPlayerMotionEvent(NeonPlayerMotionEvent event) {
    if (!event.isPre()) return;

    event.setOnGround(true);
    mc.thePlayer.motionY = 0.0;

    getNeon().logChat(getNeon().getUsername());
}