The identity of the window that raised this notification.
This will always be a window of the current application - but could have been raised by an instance of this application running on a different machine.
Optional originThe origin of the notification, which is the url of the window that raised the notification. This property is optional to support backward compatibility with sources that do not have the origin starting with version 2.7.1.
For notifications that have originated from an application running on the same machine as the provider.