in lib/src/server/sse_handler.dart [164:177]
void _close() {
if (!_closedCompleter.isCompleted) {
_closedCompleter.complete();
// Cancel any existing timer in case we were told to explicitly shut down
// to avoid keeping the process alive.
_keepAliveTimer?.cancel();
_sink.close();
if (!_outgoingController.isClosed) {
_outgoingStreamQueue.cancel(immediate: true);
_outgoingController.close();
}
if (!_incomingController.isClosed) _incomingController.close();
}
}