public void setSampleUnit(TimeUnit sampleUnit) {
		Assert.isTrue(sampleUnit == TimeUnit.SECONDS ||
				sampleUnit == TimeUnit.MILLISECONDS ||
				sampleUnit == TimeUnit.NANOSECONDS,
				"Throughput must be reported in SECONDS, MILLISECONDS, or NANOSECONDS");
		this.sampleUnit = sampleUnit;
	}
Create a {@literal ThroughputSamplerMessageHandler} using the {@code String} {@literal START} as the start
message and the {@code String} {@literal END} as the end message and measure throughput in seconds.
extensions/spring-xd-extension-throughput/src/main/java/org/springframework/xd/integration/throughput/ThroughputSamplerMessageHandler.java