GenerousVillagers/data/minecraft/villager_trade/smith/2/iron_ingot_emerald.json

{
    "gives": {
        "id": "minecraft:emerald"
    },
    "max_uses": 4096,
    "wants": {
        "count": 4,
        "id": "minecraft:iron_ingot"
    },
    "xp": 10
}