public static short accountIdFromStatsAccountKey(String accountKey) {
    return Short.valueOf(accountKey.substring(2, accountKey.length() - 1));
  }
Return account id from account key of stats report. It's the opposite of {@link #statsAccountKey}.
@param accountKey the account key of stats report.
@return The account id.
ambry-utils/src/main/java/com/github/ambry/utils/Utils.java