@ServiceActivator
	public Message<?> process(Message<?> message) {
		if (message != null) {
			this.counterRepository.increment(computeMetricName(message));
		}
		return message;
	}
Counts the number of non-null messages using an underlying {@link CounterRepository}.
spring-xd-analytics/src/main/java/org/springframework/xd/analytics/metrics/integration/MessageCounterHandler.java