@Override
    protected Traverser.Admin<S> processNextStart() {
        return PathProcessor.processTraverserPathLabels(super.processNextStart(), this.keepLabels);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/filter/WherePredicateStep.java