content: {
    "$schema": "https://json-schema.org/draft/2019-09/schema",
    "widgets": {
      "DataArray": {
        "inherits": [
          "VtkWidget"
        ],
        "properties": {
          "_model_name": "DataArray",
          "data": {
            "type": "dataunion"
          },
          "name": {
            "allowNull": true,
            "default": null,
            "type": "string"
          }
        }
      },
      "DataContainer": {
        "inherits": [
          "VtkWidget"
        ],
        "properties": {
          "_model_name": "DataContainer",
          "attributes": {
            "type": "object"
          },
          "data_arrays": {
            "items": {
              "type": "widgetRef",
              "widgetType": "DataArray"
            },
            "type": "array"
          },
          "kind": {
            "type": "string"
          }
        }
      },
      "DataSet": {
        "inherits": [
          "VtkWidget"
        ],
        "properties": {
          "pieces": {
            "items": {
              "type": "widgetRef",
              "widgetType": "Piece"
            },
            "type": "array"
          }
        }
      },
      "ImageData": {
        "inherits": [
          "DataSet"
        ],
        "properties": {
          "_model_name": "ImageData",
          "origin": {
            "items": [
              {
                "type": "float"
              },
              {
                "type": "float"
              },
              {
                "type": "float"
              }
            ],
            "type": "array"
          },
          "spacing": {
            "items": [
              {
                "type": "float"
              },
              {
                "type": "float"
              },
              {
                "type": "float"
              }
            ],
            "type": "array"
          },
          "whole_extent": {
            "items": [
              {
                "type": "float"
              },
              {
                "type": "float"
              },
              {
                "type": "float"
              },
              {
                "type": "float"
              },
              {
                "type": "float"
              },
              {
                "type": "float"
              }
            ],
            "type": "array"
          }
        }
      },
      "Piece": {
        "help": "This text describes the Piece widget",
        "inherits": [
          "VtkWidget"
        ],
        "properties": {
          "_model_name": "Piece",
          "attributes": {
            "default": {
              "foo": "bar"
            },
            "type": "object"
          },
          "data": {
            "help": "This text describes the data attribute",
            "items": {
              "type": "widgetRef",
              "widgetType": "DataContainer"
            },
            "type": "array"
          }
        }
      },
      "UnstructuredGrid": {
        "inherits": [
          "DataSet"
        ],
        "properties": {
          "_model_name": "UnstructuredGrid"
        }
      },
      "VtkWidget": {
        "inherits": [
          "Widget"
        ],
        "properties": {
          "model_module_name": "test-widget",
          "model_module_version": "1.0.0",
          "model_view_version": {
            "allowNull": true,
            "default": null,
            "type": "string"
          },
          "view_module_name": "test-widget"
        }
      }
    }
  }