json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "type": "object",
      "properties": {
          "fileSize": {
              "type": "number"
          },
          "contentType": {
              "type": "string",
              "maxLength": 1024
          },
          "fileDimensions": {
              "type": "object",
              "properties": {
                  "width": {
                      "type": "number"
                  },
                  "height": {
                      "type": "number"
                  }
              }
          }
      }
  }