@Override
  public int clusterSize() {
    return Integer.parseInt(KafkaConfig.TOPIC_DEFAULT_REPLICATION_FACTOR());
  }
Produces a message to the provided topic partition.
@param topicName the topic to produce messages to
@param partitionId the topic partition to produce messages to
@param key the key in the message
@param val the value in the message
samza-test/src/test/java/org/apache/samza/test/framework/StreamApplicationIntegrationTestHarness.java