You made a nice quess because internally Mendix works like this, but i won’t let you do it in a microflow, only in Java. The value you is is the WorkflowUserTask/id.
Expand the WorkflowUserTask in the debugger and choose an attribute (like name or description) with a unique value to retrieve it. Like [Name=’Process’]
Or use a head/tail on the list.
Or make a java-action.
return Core.retrieveId(getContext(), Core.createMendixIdentifier('1232132132131'));