code: public static byte[] journalIdStringToBytes(String jid) {
      byte[] byteArray = new byte[jid.length()];
      for (int i = 0; i < jid.length(); i++) {
        byteArray[i] = (byte) jid.charAt(i);
      }
      return byteArray;
    }
docs: Translates String journal id into byte[].
  We assume the id is ascii.