add method
Adds a disposable to this container or disposes it if this bag has been disposed or is disposing.
disposable
must be a StreamSubscription or a Sink.
Returns true if disposable
was added successfully.
Implementation
@override
Future<bool> add(Object disposable) async {
_guardType(disposable);
final resources = _validResourcesOrNull();
if (resources == null) {
await _disposeOne(disposable);
return false;
}
return resources.add(disposable);
}