onStop method
Releases reception resources, allowing retries when cleanup fails.
Implementation
@override
Future<void> onStop() async {
if (!identical(_owner, this)) return;
_accepting = false;
try {
await _subscription?.cancel();
_subscription = null;
} finally {
await _platform.stopListening();
}
// A failed stop must retain ownership until cleanup is retried.
_owner = null;
}