@Override
	protected MessageBus getMessageBus() {
		if (testMessageBus == null) {
			testMessageBus = new RabbitTestMessageBus(rabbitAvailableRule.getResource(), getCodec());
		}
		return testMessageBus;
	}
@author Mark Fisher
@author Gary Russell
spring-xd-dirt/src/test/java/org/springframework/xd/dirt/integration/bus/rabbit/RabbitMessageBusTests.java