json_schema: {
      "$schema": "http://json-schema.org/draft-04/schema#",
      "type": "object",
      "properties": {
          "level": {
              "type": "string",
              "enum": [
                  "info",
                  "warning",
                  "error",
                  "critical"
              ]
          },
          "state": {
              "type": "string",
              "enum": [
                  "new",
                  "acknowledged",
                  "resolved"
              ]
          },
          "subject": {
              "type": "string",
              "minLength": 1,
              "maxLength": 255
          },
          "message": {
              "type": "string"
          }
      },
      "required": [
          "level",
          "state",
          "subject"
      ],
      "additionalProperties": false
  }