private @NotNull List<Element> doResolve(@NotNull Element original, URL base) throws XIncludeException, MalformedURLException {
    Stack<URL> bases = new Stack<>();
    if (base != null) {
      bases.push(base);
    }
    return resolve(original, bases);
  }
private @NotNull List<Element> doResolve(@NotNull Element original, URL base)