@Override
  public void setFailureCause(Throwable throwable) {
    super.setFailureCause(throwable); // notify the BEM
  }
Invoked by {@link KafkaConsumerProxy} to notify the consumer of failure, so it can relay and stop the BEM polling.
@param throwable the cause of the failure of the proxy
samza-kafka/src/main/java/org/apache/samza/system/kafka/KafkaSystemConsumer.java