code: private boolean isNonceableLink(HtmlOpenTagNode tag) {
      String relAttrValue = getStaticDirectAttributeValue(tag, "rel");
      if (relAttrValue == null) {
        return false;
      }
      if (Ascii.equalsIgnoreCase("import", relAttrValue)) {
        return true;
      }
      if (Ascii.equalsIgnoreCase("preload", relAttrValue)) {
        String asAttrValue = getStaticDirectAttributeValue(tag, "as");
        if (asAttrValue == null) {
          return false;
        }
        return Ascii.equalsIgnoreCase(asAttrValue, "script")
            || Ascii.equalsIgnoreCase(asAttrValue, "style");
      }
      return false;
    }
docs: See https://html.spec.whatwg.org/#obtaining-a-resource-from-a-link-element