Define a
wt.org.WTUser taskComplete
variable at the workflow process template level.
In your activity template, go to the "Variables" tab to copy that variable into and out of your task.
Next, go to the activity template "Transitions" tab, select the transition you are interested in (or use the "Complete" transition if you want to check this for all transitions no matter what on completion), and add this code.
taskComplete = (wt.org.WTUser)wt.session.SessionMgr.getPrincipal();
This will copy the current user who clicked task complete causing that transition to fire from the transition to the activity and from the activity up to the process where you can use it as a process variable in later robots.
Try it.
