json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "type": "object",
      "properties": {
          "key": {
              "type": "string",
              "minLength": 1,
              "maxLength": 255
          },
          "value": {}
      },
      "additionalProperties": false,
      "required": [
          "key"
      ]
  }