Its just used for the ws start process, and not for the ws call step. So if you don't have any webservice process in your application you can replace the jar by anything. And else you have to test if the process still work as expected.
There exists a bugreport for that problem: **#25110 Use of a newer Apache POI version not possible**.
You can track it on soreconnect and optionally enable e-mail notification on status changes. Please contact our PO Product Owner (Reto) if you want to negotiate the backlog priorization of this bug.