Multiple shipments with FILO order

Hello everybody

I am trying to solve a problem statement with the help of jsprit.

There is a depot.
Identical items need to be delivered or picked up. An item can have two states: Bad or good.

Bad items need to be collected from different locations and they end up at the depot.
Good items can originate from the depot or different locations and they end up at various other locations.

Items are identical, hence any good item can be dropped where a good item needs to be dropped. However, the items are big in size and the last item in has to be the first item out. So, if a good item has gone in, then the next task has to be to drop a good item. We cannot pick up a bad item after a good item, since all bad items go to the depot and good items are not dropped at the depot.

How can I model this with jsprit? Thanks in advance.