static String checkCommentData(final String data) {
    String reason;
    if ((reason = checkCharacterData(data)) != null) {
      return reason;
    }

    if (data.contains("--")) {
      return "Comments cannot contain double hyphens (--)";
    }
    if (data.endsWith("-")) {
      return "Comment data cannot end with a hyphen.";
    }

    // If we got here, everything is OK
    return null;
  }
static String checkCommentData(final String data)