[1.20.4] Add Custome trades to traders

looking around for the capabilities thing i found a piece of code and find this piece of code 

	//########## ########## ########## ##########

@SubscribeEvent
public static void addCustomTrades(VillagerTradesEvent event) {
if(event.getType() == VillagerProfession.FLETCHER) {
System.out.println("\n\n### VillagerProfession.FLETCHER \n\n");//<-----------
Int2ObjectMap<List<VillagerTrades.ItemListing>> trades = event.getTrades();
ItemStack stack = new ItemStack(ItemInit.ARROW_STEEL.get(), 16);
int villagerLevel = 1;
trades.get(villagerLevel).add((trader, rand) -> new MerchantOffer(
new ItemStack(Items.EMERALD, 2),
stack,1,3,0.02F));
}

if(event.getType() == VillagerProfession.TOOLSMITH) {
System.out.println("\n\n### VillagerProfession.TOOLSMITH \n\n");//<-----------
Int2ObjectMap<List<VillagerTrades.ItemListing>> trades = event.getTrades();
ItemStack stack = new ItemStack(ItemInit.INGOT_STEEL.get(), 1);
int villagerLevel = 1;
trades.get(villagerLevel).add((trader, rand) -> new MerchantOffer(
new ItemStack(Items.EMERALD, 2),
stack,10,8,0.02F));
}
	}
	//########## ########## ########## ##########
	

the event is aknoledge and execute when the maps load 

	### VillagerProfession.FLETCHER 
	### VillagerProfession.TOOLSMITH 

//##########

But is not working 

is a random piece of code is not working 

could it be than this code is old 1.18 and no valid anymore for 1.20.4

or the thing are this numbers 

stack,10,8,0.02F)); 

i dont know what this numbers means 

##########

the question is ¿how to add things to the villager traders 

thanks for your attention