minecraft-assets/data/minecraft/recipes/black_dye_from_wither_rose.json

{
  "type": "minecraft:crafting_shapeless",
  "category": "misc",
  "group": "black_dye",
  "ingredients": [
    {
      "item": "minecraft:wither_rose"
    }
  ],
  "result": {
    "item": "minecraft:black_dye"
  }
}