minecraft-kajetans-core-mod/src/main/resources/class_transformer/craft.js

var transformerName = "Dedicated Server Transformer";
var ASMAPI = Java.type('net.minecraftforge.coremod.api.ASMAPI');
var Opcodes = Java.type('org.objectweb.asm.Opcodes');
var VarInsnNode = Java.type("org.objectweb.asm.tree.VarInsnNode");
var MethodInsnNode = Java.type("org.objectweb.asm.tree.MethodInsnNode");
var LineNumberNode = Java.type("org.objectweb.asm.tree.LineNumberNode");
var FieldInsnNode = Java.type("org.objectweb.asm.tree.FieldInsnNode");
var InsnNode = Java.type("org.objectweb.asm.tree.InsnNode");

function initializeCoreMod() {
    return {
        transformerName: {
            'target': {
                'type': 'CLASS',
                'name': 'net.minecraft.inventory.container.WorkbenchContainer'
            },
            'transformer': function (classNode) {
                var methods = classNode.methods;

                var targetMethodName = ASMAPI.mapMethod("func_217066_a"); // no name set yet
                for (var i in methods) {
                    var method = methods[i];
                    if (method.name.equals(targetMethodName)) {
                        transform(method);
                        break;
                    }
                }
                return classNode;
            }
        }
    };
}

function transform(method) {
    var instrList = method.instructions;
    instrList.clear();
    instrList.add(new VarInsnNode(Opcodes.ILOAD, 0));
    instrList.add(new VarInsnNode(Opcodes.ALOAD, 1));
    instrList.add(new VarInsnNode(Opcodes.ALOAD, 2));
    instrList.add(new VarInsnNode(Opcodes.ALOAD, 3));
    instrList.add(new VarInsnNode(Opcodes.ALOAD, 4));
    instrList.add(new MethodInsnNode(Opcodes.INVOKESTATIC, "me/kcm/Hooks",
            "onCraft",
            "(ILnet/minecraft/world/World;Lnet/minecraft/entity/player/PlayerEntity;Lnet/minecraft/inventory/CraftingInventory;Lnet/minecraft/inventory/CraftResultInventory;)V",
            false));
    instrList.add(new InsnNode(Opcodes.RETURN));
}