I’m currently working on a Workflow where I need a list of distinct values.

I need to retrieve a collection of distinct suppliers from a set of Purchase Requisition Lines.
I’m currently using an API element to fetch all Purchase Req Lines that meet a certain set of condition e.g. from a specific site. For those Purchase Req Lines the same Vendor/Supplier exists multiple times. However I actually need a distinct list of VendorNo in a collection for a Sub Process.
I have tried multiple ways to achieve this but I haven't succeeded yet.

Anybody have a suggestion for a solution?