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

{
  "type": "minecraft:crafting_shapeless",
  "category": "misc",
  "group": "black_dye",
  "ingredients": [
    "minecraft:wither_rose"
  ],
  "result": {
    "count": 1,
    "id": "minecraft:black_dye"
  }
}