public void OnDownstreamFinish()
{
// Do Nothing until `timeout` to try and intercept completion as downstream,
// but cancel stream after timeout if inlet is not closed to prevent deadlock.
Materializer.ScheduleOnce(_timeout, () =>
{
var cb = GetAsyncCallback(() =>
{
if (!IsClosed(_nextElem))
{
FailStage(new InvalidOperationException($"unfoldFlow source's inner flow canceled only upstream, while downstream remain available for {_timeout}"));
}
});
cb();
});
}