Создание своих профессий для жителей

public class VillagerTrades
{
    public static class ItemstackForItemstack implements EntityVillager.ITradeList
    {
        public ItemStack buyingItem;
        public ItemStack sellingItem;
        public EntityVillager.PriceInfo buyAmounts;
        public EntityVillager.PriceInfo sellAmounts;

        // buyItem - покупаемое жителем, sellItem - продаваемое жителем, buyAmounts и sellAmounts - диапазоны количеств
        public ItemstackForItemstack(@Nonnull ItemStack buyItem, @Nonnull ItemStack sellItem, @Nonnull EntityVillager.PriceInfo buyAmounts,  @Nonnull EntityVillager.PriceInfo sellAmounts)
        {
            this.buyingItem = buyItem;
            this.sellingItem = sellItem;
            this.buyAmounts = buyAmounts;
            this.sellAmounts = sellAmounts;
        }

        @Override
        public void addMerchantRecipe(IMerchant merchant, MerchantRecipeList recipeList, Random random)
        {
            recipeList.add(new MerchantRecipe(addAmount(this.buyingItem, this.buyAmounts.getPrice(random)), addAmount(this.sellingItem, this.sellAmounts.getPrice(random))));
        }
    }
  
    // Вспомогательный метод для добавления случайного количества к итему
    public static ItemStack addAmount(ItemStack item, int amount)
    {
        ItemStack s2 = item.copy();
        s2.setCount(amount);
        return s2;
    }
  
}

public class VillagerRegister {
    public static VillagerRegistry.VillagerProfession PROF_EXAMPLE;
  
    public static void registerVillagers() {
        PROF_EXAMPLE = new VillagerRegistry.VillagerProfession(ExampleMod.MODID + ":example", ExampleMod.MODID + ":textures/models/villager_example.png", ExampleMod.MODID + ":textures/models/villager_example_zombie.png");
        ForgeRegistries.VILLAGER_PROFESSIONS.register(PROF_EXAMPLE);
  
        VillagerRegistry.VillagerCareer career_example = new VillagerRegistry.VillagerCareer(PROF_EXAMPLE, ExampleMod.MODID + ".example");
        career_example.addTrade(1,
                new VillagerTrades.ItemstackForItemstack(Items.DIAMOND, Items.EMERALD, new EntityVillager.PriceInfo(1, 2), new EntityVillager.PriceInfo(3, 4))
        );
    }
}

public void init(FMLInitializationEvent event)
    {
        VillagerRegister.registerVillagers();
}