[oozie] Empty delete action results in <delete path='${nameNode}/user/${wf:user()}/'/>

Having an empty text field when configuring a "Delete path" in an Oozie shell action results in a workflow.xml that contains a

<delete path='${nameNode}/user/${wf:user()}/'/>

The same applies to a prepare element in a pig action for instance.

This behavior is kind of unexpected to me and I think it should be improved by having the parameter defined as required.