add On Document Coordinator Empty Listener
abstract fun addOnDocumentCoordinatorEmptyListener(@NonNull listener: DocumentCoordinator.OnDocumentCoordinatorEmptyListener)
Registers a OnDocumentCoordinatorEmptyListener to get notified when document gets visible in the manager. If the listener has been registered previously, this method will be a no-op.
Parameters
listener
Listener to register. Must be non-null.