code: @Override
      public void findDefaultChannel(MessageBroker broker, Service service) {
          if (!CollectionUtils.isEmpty(broker.getDefaultChannels())) {
              return;
          }
  
          Iterator<String> channels = broker.getChannelIds().iterator();
          while (channels.hasNext()) {
              Endpoint endpoint = broker.getEndpoint(channels.next());
              if (endpoint instanceof AMFEndpoint && isPollingEnabled(endpoint)) {
                  service.addDefaultChannel(endpoint.getId());
                  return;
              }
          }
          log.warn("No appropriate default channels were detected for the MessageService.  "
              + "The channels must be explicitly set on any exported service.");
      }
docs: Tries to find a sensible default AMF channel for the default MessageService
  
  If a application-level default is set on the MessageBroker, that will be used. Otherwise will use the first
  AMFEndpoint from services-config.xml that it finds with polling enabled.
  
  @param broker
  @param service