attach
Chains the queue's numInQ time-weighted response to the aggregate's aggregateNumberBackOrdered, and the queue's timeInQ per-observation response to the aggregate's aggregateAvgCustomerWaitTime.
The runtime is checks downcast from the queue's exposed read-only TWResponseCIfc / ResponseCIfc views to the concrete TWResponse / Response types — required to call observe(). Safe because KSL Queue always uses TWResponse / Response internally.