private Navigatable getNavigatable(@NotNull HierarchyNodeDescriptor descriptor) {
    if (descriptor instanceof Navigatable && descriptor.isValid()) {
      return (Navigatable)descriptor;
    }

    PsiElement element = getElementFromDescriptor(descriptor);
    if (element instanceof NavigatablePsiElement && element.isValid()) {
      return (NavigatablePsiElement)element;
    }
    return null;
  }
private Navigatable getNavigatable(@NotNull HierarchyNodeDescriptor descriptor)