[
  {
    "key": "id",
    "label": "ID (if you're seeing this, it means custom fields work!)",
    "type": "number"
  },
  {
    "key": "color",
    "label": "Color",
    "type": "string"
  },
  {
    "key": "age",
    "label": "Age",
    "type": "number"
  }
]