As part of a Plone migration over plone.restapi I need to preserve and restore the original ordering of items within folders. I am reading this here but I am not getting the point with sub_ids here:
I'm guessing you're looping over the original content item and issue a PUT or POST to create them?
If so, then you can "move" the item to the bottom position using:
PATCH /plone/[id of the container]
{
"ordering": {"obj_id": "id of item", "delta": "bottom"}
}
I'd expect the item to be at the bottom position already, as that is the default position an item is created at in the UI.