private int roundRobin() {
			int result = roundRobinCount.incrementAndGet();
			if (result == Integer.MAX_VALUE) {
				roundRobinCount.set(0);
			}
			return result;
		}
Fetches partition data, throwing an exception if the expected number is not met after a number of
subsequent retries
@param topicName topic
@param expectedNumber expected number of partitions. If less or equal to 0, check is suppressed.
@return the partitions
spring-xd-messagebus-kafka/src/main/java/org/springframework/xd/dirt/integration/kafka/KafkaMessageBus.java