static String getBackupFilename(int version, long modifiedTimeInSec) {
    String timestamp = LocalDateTime.ofEpochSecond(modifiedTimeInSec, 0, zoneOffset).format(TIMESTAMP_FORMATTER);
    return version + SEP + timestamp;
  }
Generate the backup filename with version number and modified time.
@param version The version of backup filename
@param modifiedTimeInSec modified time in seconds
@return The filename.
ambry-account/src/main/java/com/github/ambry/account/BackupFileManager.java