Hello! So, I am making my own mod, and I need to edit a bit of the MC sourcecode (not much just add an item to a mob's drop), but I don't know how I can edit them. I tried searching up some guides but I didn't find any good ones.

private static final Item[] witchDrops = new Item[] {Items.glowstone_dust, Items.sugar, Items.redstone, Items.spider_eye, Items.glass_bottle, Items.gunpowder, Items.stick, Items.stick};

This is all I what I want to edit, add one item into there but idk how.
Also if you know a way to add an Item to the witchDrops, but not editing a MC sourcecode, it would be awesome :P

Thanks