onListen property Null safety

@override ControllerCallback? onListen

The callback which is called when the stream is listened to.

May be set to null, in which case no callback will happen.

Implementation

@override
ControllerCallback? get onListen => _controller.onListen;

@override void onListen=(void onListenHandler()?)

The callback which is called when the stream is listened to.

May be set to null, in which case no callback will happen.

Implementation

@override
set onListen(void Function()? onListenHandler) {
  _controller.onListen = onListenHandler;
}