docs: public static String escapeHtmlAttribute(SoyValue value) {
      value = normalizeNull(value);
      if (isSanitizedContentOfKind(value, SanitizedContent.ContentKind.HTML)) {
        // |escapeHtmlAttribute should only be used on attribute values that cannot have tags.
        return stripHtmlTags(value.coerceToString(), null, true);
      }
      return escapeHtmlAttribute(value.coerceToString());
    }