minecraft-assets/assets/minecraft/recipes/gray_wool.json

{
  "type": "crafting_shapeless",
  "group": "wool",
  "ingredients": [
    {
      "item": "minecraft:dye",
      "data": 8
    },
    {
      "item": "minecraft:wool",
      "data": 0
    }
  ],
  "result": {
    "item": "minecraft:wool",
    "data": 7
  }
}