code: private void handlePresenceAnnouncement(SsdpResponse response) {
      SsdpServiceAnnouncement ssdpServiceAnnouncement = response.toServiceAnnouncement();
      if (ssdpServiceAnnouncement.getSerialNumber() == null) {
        callback.onFailed(new NoSerialNumberException());
        return;
      }
      if (cache.containsKey(ssdpServiceAnnouncement.getSerialNumber())) {
        callback.onServiceAnnouncement(ssdpServiceAnnouncement);
      } else {
        requests.add(DiscoveryRequest.builder().serviceType(ssdpServiceAnnouncement.getServiceType()).build());
      }
    }
docs: Handle presence announcement Datagrams.
  
  @param response the incoming announcement