@Override
    public void dropLabels(final Set<String> labels) {
        if (!labels.isEmpty())
            this.path = path.retract(labels);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/traverser/B_LP_O_S_SE_SL_Traverser.java