public CheckpointV2 readCheckpointV2File(File storagePartitionDir) {
    File checkpointFile = new File(storagePartitionDir, CHECKPOINT_FILE_NAME);
    if (checkpointFile.exists()) {
      String serializedCheckpointV2 = new FileUtil().readWithChecksum(checkpointFile);
      return new CheckpointV2Serde().fromBytes(serializedCheckpointV2.getBytes());
    } else {
      return null;
    }
  }
Read and return the {@link CheckpointV2} from the directory's {@link #CHECKPOINT_FILE_NAME} file.
If the file does not exist, returns null.

@param storagePartitionDir store directory to read the checkpoint file from
@return the {@link CheckpointV2} object retrieved from the checkpoint file if found, otherwise return null
samza-core/src/main/java/org/apache/samza/storage/StorageManagerUtil.java