Body

{
  "custom_fields": [
    {
      "_id": "5853d8c2edb7aacab9000045",
      "name": "test_field_1",
      "label": "Test Field 1",
      "description": "Field 1 description",
      "type": "string",
      "is_url": false
    },
    {
      "_id": "5853d8c2edb7aacab9000046",
      "name": "test_field_2",
      "label": "Test Field 2",
      "description": "Field 2 description",
      "type": "string",
      "is_url": true
    },
    {
      "_id": "5853d8c2edb7aacab9000047",
      "name": "test_field_3",
      "label": "Test Field 3",
      "description": "Field 3 description",
      "type": "string",
      "is_url": false
    }
  ]
}