anchor.diff:      // Can't send to IPv6 any address.
       if (incoming.address != InternetAddress.anyIPv6) {
         _sockets.add(incoming);
  +    } else {
  +      _toBeClosed.add(incoming);
       }
   
       _mDnsAddress ??= incoming.address.type == InternetAddressType.IPv4
  
positive.code:   bool _starting = false;
    bool _started = false;
    final List<RawDatagramSocket> _sockets = <RawDatagramSocket>[];
    final LookupResolver _resolver = LookupResolver();
    final ResourceRecordCache _cache = ResourceRecordCache();
    final RawDatagramSocketFactory _rawDatagramSocketFactory;
  
negative.code:     for (final RawDatagramSocket socket in _sockets) {
        socket.close();
      }
      _sockets.clear();
  
      for (final RawDatagramSocket socket in _toBeClosed) {
        socket.close();
      }
      _toBeClosed.clear();
  
      _resolver.clearPendingRequests();
  
  