message: added duration format to support ISO8601 strings
diff: "duration": {
  "type": "string",
  "description": "ISO8601 formatted string that represents a duration.",
  - "pattern": "^P(\\d+Y)?(\\d+M)?(\\d+D)?(T(\\d+H)?(\\d+M)?(\\d+(\\.\\d+)?S)?)?$"
  + "pattern": "^P(\\d+Y)?(\\d+M)?(\\d+D)?(T(\\d+H)?(\\d+M)?(\\d+(\\.\\d+)?S)?)?$",
  + "format": "duration"
  }
  },
  "required": [
  "duration": {
  "type": "string",
  "description": "ISO8601 formatted string that represents a duration.",
  - "pattern": "^P(\\d+Y)?(\\d+M)?(\\d+D)?(T(\\d+H)?(\\d+M)?(\\d+(\\.\\d+)?S)?)?$"
  + "pattern": "^P(\\d+Y)?(\\d+M)?(\\d+D)?(T(\\d+H)?(\\d+M)?(\\d+(\\.\\d+)?S)?)?$",
  + "format": "duration"
  },
  "parameters": {
  "description": "List of key value pairs.",
  