query ListCustomFields {
  listCustomFields {
    id
    name
    label
    description
    fieldType
    required
  }
}

{
  "data": {
    "listCustomFields": [
      {
        "id": "id",
        "name": "string",
        "label": "string",
        "description": "string",
        "fieldType": "string",
        "required": true
      }
    ]
  }
}