Indicates whether each notification message results in a new entry on the notification center on Android.
If not set, each request creates a new notification. If set, and a notification with the same tag is already
being shown, the new notification replaces the existing one in notification center.
Indicates whether each notification message results in a new entry on the notification center on Android. If not set, each request creates a new notification. If set, and a notification with the same tag is already being shown, the new notification replaces the existing one in notification center.