@Override
    public int hashCode() {
        int result = this.getClass().hashCode();
        for (final String label : this.getLabels()) {
            result ^= label.hashCode();
        }
        return result;
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/util/AbstractStep.java