I'm curious if anyone has used the join spec field in join nodes to change the simulation behavior of a join node. It seems like it would be useful to add some additional logic to the join node. At the moment, if "Is Combine Duplicate" the join node is supposed to package all incoming objects in an array and send them through. But what if i want only one (or a few objects) to come through. 

Currently I'm using another action to complete that behavior, but it would be great if I could build that into the join node.

The text in the join node field says " A ValueSpecification giving the condition under which the JoinNode will offer a token on its Activity Edge. If no join Spec is specified, then the JoinNode will offer an outgoing token if tokens are offered on all of its incoming Activity Edges (an "and" condition)."

I tried building in some groovy login in that field, but it didn't seem to do much. I'm not sure what all this field is capable of doing. So I was curious if anyone had any working examples of implementing something using that field.