renewable-resources/data/renewable/recipe/sponge.json

{
  "type": "minecraft:crafting_shaped",
  "category": "building",
  "pattern": [
    "WWW",
    "WSW",
    "WWW"
  ],
  "key": {
    "W": "minecraft:white_wool",
    "S": "minecraft:slime_ball"
  },
  "result": {
    "id": "minecraft:sponge",
    "count": 1
  }
}