code: private void addDefaultChannels(MessageBroker broker, Service service) {
          List<String> defaultChannelList = new ArrayList<String>();
          for (String channelId : this.defaultChannels) {
              Assert.isTrue(broker.getChannelIds().contains(channelId), "The channel " + channelId + " is not known to the MessageBroker "
                  + broker.getId() + " and cannot be set as a default channel" + " on the " + getServiceClassName());
              defaultChannelList.add(channelId);
          }
          service.setDefaultChannels(defaultChannelList);
      }
docs: Adds the default channels to the {@link Service} being configured. The <code>defaultChannels</code> will be
  validated to ensure they exist in the {@link MessageBroker} before they are set.
  
  @param broker the newly configured MessageBroker
  @param remotingService the newly created Service