@Override
  public void stop() {
    LOG.info("Stopping in memory system producer for {}", systemName);
  }
Stop the SystemProducer. After this method finished, the system should have completed all necessary work, sent
any remaining messages and will not receive any new calls to the send method.
samza-core/src/main/java/org/apache/samza/system/inmemory/InMemorySystemProducer.java