@Override
		protected synchronized boolean doSend(Message<?> message, long timeout) {
			try {
				headersList.put(message.getHeaders());
			}
			catch (InterruptedException ie) {
				Thread.currentThread().interrupt();
			}
			blockGenerator.addDataWithCallback(message.getPayload(), message.getHeaders());
			return true;
		}
The {@link DirectChannel} that stores the received messages into Spark's memory.
spring-xd-dirt/src/main/java/org/springframework/xd/dirt/plugins/spark/streaming/MessageBusReceiver.java