All the tutorials are pre-registry change-- VillagerRegistry.instance().registerVillageTradeHandler() doesn't exist anymore, and copying the vanilla code caused Forge to punch my computer.

Um... I believe somewhere in the forge docs I saw that you can register a villager profession. Idk if that was what you were looking for...

If you want to add trades to existing villager professions, you need:

1. Implement EntityVillager.ITradeList

2. Get the profession from ForgeRegistries.VILLAGER_PROFESSIONS

3. Get career from the profession

4. add the ITradeList to the career - #addTrade.

 

Example below:

Implementation which adds 60 emeralds -> 1 Wither skull trade:

public class Trades implements EntityVillager.ITradeList
{
   @Override
   public void addMerchantRecipe(IMerchant merchant, MerchantRecipeList recipeList, Random random)
   {
      recipeList.add(new MerchantRecipe(new ItemStack(Items.EMERALD,60),new ItemStack(Items.SKULL,1,1)));
   }
}

 

Then getting a specific profession - nitwit in this case:

VillagerRegistry.VillagerProfession nitwit=ForgeRegistries.VILLAGER_PROFESSIONS.getValue(new ResourceLocation("minecraft:nitwit"));

 

And adding the trade to career with id "5":

nitwit.getCareer(5).addTrade(1,new Trades());

 

Figure out desired career and profession by inspecting vanilla classes.