@Override
    public CollectingBarrierStep<S> clone() {
        final CollectingBarrierStep<S> clone = (CollectingBarrierStep<S>) super.clone();
        clone.traverserSet = (TraverserSet<S>) this.traversal.getTraverserSetSupplier().get();
        clone.barrierConsumed = false;
        return clone;
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/util/CollectingBarrierStep.java