@Override
    public MemoryComputeKey<TraverserSet<S>> getMemoryComputeKey() {
        return MemoryComputeKey.of(this.getId(), (BinaryOperator) Operator.addAll, false, true);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/util/CollectingBarrierStep.java