absence approval: no requestors role details to choose

Summary:

Our customer has the requirement, that some absence types can only be entered in the system by an HR User.

Visibility is driven by the absence type - that's all done and working.

The approval is the problem.

I want to set up the approval, that if HR Key User (custom role), absence request gets auto approved. If other roles try to request the absence, it should automatically fail.

In BPM worklist I can't find the attribute "Requestor's Role Details. Role Name" like for e.g. AddNewPersonApproval.

Is there a similar attribute I can choose to specify the approval workflow rules for absence on the requestor's role?