dev/defs/shapes/shape.json

{
  "name": "Shape",
  "key": {
    "int": 3,
    "string": "shape"
  },
  "extends": "drawable.json",
  "properties": {
    "length": {
      "type": "double",
      "initialValue": "0",
      "key": {
        "int": 781,
        "string": "length"
      },
      "bindable": true,
      "passthrough": true
    }
  }
}