Gather an attribute from a workflow task (Such as Completed By, Completed Date, & Comments) and write it to a document attribute

Hello all,

First post on here... I am looking for guidance on how to gather attributes from a workflow task (such as task completer, when they completed it, and comments) and drive those comments to an attribute on the affected objects.  Example... Promotion request for a document.  Document is promoted, approvers complete their approval task.  I want to be able to put those attributes back into the document before the set state robot runs on the promotion request.

I figure I will have to have some sort of expression robot, but what else?  Anyone else done this sort of thing?

Jim Bailey
Systems Analyst
NASA GRC / Vantage Partners LLC