key property
Unique ID for this action. This ID will be sent back in the action handler defined in FlutterLocalNotificationsPlugin.
If LinuxNotificationDetails.keyAsIconName is true,
the server will attempt to interpret key as a named icon.
label will be used to annotate the icon for accessibility purposes.
The icon name should be compliant with the Freedesktop.org Icon Naming Specification https://specifications.freedesktop.org/icon-naming-spec/latest/
Implementation
final String key;