@Override
        public Traversal<Vertex, ? extends Property<Object>> get_g_V_properties_hasValueXnull_nullX() {
            return g.V().properties().hasValue(null,null);
        }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/filter/HasTest.java