{
  "id": "<string>",
  "type": "customfields",
  "attributes": {
    "name": "<string>",
    "description": "<string>",
    "required": true,
    "display_in_checkout": true,
    "options": "<array>",
    "default_value": "<string>",
    "order_index": 123,
    "custom_validation": "<string>"
  },
  "links": {
    "self": "<string>"
  }
}