private static String buildCommentString(@Nullable String classAttr, @Nullable String idAttr) {
    StringBuilder builder = new StringBuilder();
    if (!Strings.isEmpty(idAttr)) {
      builder.append('#').append(idAttr);
    }
    if (!Strings.isEmpty(classAttr)) {
      builder.append('.').append(classAttr);
    }
    return builder.toString();
  }
private static String buildCommentString(@Nullable String classAttr, @Nullable String idAttr)