minecraft-assets/assets/minecraft/advancements/recipes/brewing/cauldron.json

{
  "rewards": {
    "recipes": [
      "minecraft:cauldron"
    ]
  },
  "criteria": {
    "has_the_recipe": {
      "trigger": "minecraft:recipe_unlocked",
      "conditions": {
        "recipe": "cauldron"
      }
    },
    "has_water_bucket": {
      "trigger": "minecraft:inventory_changed",
      "conditions": {
        "items": [
          {
            "item": "minecraft:water_bucket"
          }
        ]
      }
    }
  },
  "requirements": [
    [
      "has_the_recipe"
    ],
    [
      "has_water_bucket"
    ]
  ]
}