private static @Nullable CachedTreePresentationData readExternalPresentation(Element element) {
    var presentationChildren = element.getChildren(PRESENTATION_TAG);
    if (presentationChildren.size() != 1) return null;
    var presentations = new SmartList<CachedTreePresentationData>();
    readExternalPresentation(presentationChildren.get(0), presentations);
    return presentations.size() == 1 ? presentations.get(0) : null;
  }
private static @Nullable CachedTreePresentationData readExternalPresentation(Element element)