Loading state for tree nodes while children are loading asynchronously

Would it work if one was to set the hasCaret prop to whether or not children are available, display a spinner upon onExpand while fetching content from elsewhere, and then replace the spinner with the actual content upon completion?

If so, what would be an elegant way to display a spinner? At first glance, it seems like the only valid type of children are again tree nodes. Those could at least have a label "loading" and be disabled for the time being, however I would much rather prefer a spinner. Could the children prop be used for this?

Thanks for any hints.