@Override
    public int hashCode() {
        int result = super.hashCode();
        for (final HasContainer hasContainer : this.hasContainers) {
            result ^= hasContainer.hashCode();
        }
        return result;
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/filter/HasStep.java