private static String commitMessage(int partitionId, int messageId) {
    return String.join("_", COMMIT_PREFIX, "partition", Integer.toString(partitionId), Integer.toString(messageId));
  }
For each partition: re-process the second message (for 2 total of the second message), receive the third message.
samza-test/src/test/java/org/apache/samza/test/kafka/KafkaCheckpointManagerIntegrationTest.java