@Override
	public synchronized void stop() {
		if (this.isRunning() && messageBus != null) {
			logger.info("stopping MessageBusSender");
			messageBus.unbindProducer(outputChannelName, outputChannel);
			for (ChannelInterceptor interceptor : outputChannel.getChannelInterceptors()) {
				if (interceptor instanceof WireTap) {
					((WireTap) interceptor).stop();
				}
			}
			if (isTapEnabled()) {
				messageBus.unbindProducers(tapChannelName);
			}
			messageBus = null;
		}
		if (applicationContext != null) {
			applicationContext.close();
			applicationContext = null;
		}
		this.running = false;
	}
Add tap channel to the module's output channel.
Also, bind the tap channel to the message bus.
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/plugins/spark/streaming/MessageBusSender.java