close method
Implementation
Future<void> close() async {
if (clientsQueriesTimer != null) {
clientsQueriesTimer!.cancel();
clientsQueriesTimer = null;
}
final List<Future<void>> promises = <Future<void>>[];
for (int i = clients.length - 1; i >= 0; i--) {
promises.add(clients[i].close());
}
await Future.wait(promises);
clients.clear();
if (_httpServer != null) await _httpServer?.close();
else if (_tcpServer != null) await _tcpServer?.close();
}