notificationCount property
Sets the number of items this notification represents. May be displayed as a badge count for Launchers that support badging. See NotificationBadge. For example, this might be useful if you're using just one notification to represent multiple new messages but you want the count here to represent the number of total new messages. If zero or unspecified, systems that support badging use the default, which is to increment a number displayed on the long-press menu each time a new notification arrives.
Implementation
final int? notificationCount;