{
  "marktype": "group",
  "interactive": false,
  "items": [
    {
      "x": 1,
      "y": 1,
      "width": 100,
      "height": 100,
      "clip": true,
      "fill": {
        "gradient": "linear",
        "id": "gradient_foo",
        "stops": [
          {"offset": 0.0, "color": "red"},
          {"offset": 0.5, "color": "green"},
          {"offset": 1.0, "color": "blue"}
        ],
        "x1": 0,
        "x2": 1,
        "y1": 0,
        "y2": 0
      }
    }
  ]
}