json_schema: {
      "additionalProperties": false,
      "definitions": {
          "MySubObject": {
              "_id": "MySubObject",
              "additionalProperties": false,
              "properties": {
                  "propA": {
                      "type": "number"
                  },
                  "propB": {
                      "type": "number"
                  }
              },
              "required": [
                  "propA",
                  "propB"
              ],
              "type": "object"
          }
      },
      "properties": {
          "subA": {
              "$ref": "#/definitions/MySubObject"
          },
          "subB": {
              "$ref": "#/definitions/MySubObject"
          }
      },
      "required": [
          "subA",
          "subB"
      ],
      "type": "object"
  }