@Override
        public GraphTraversalSource getGraphTraversalSource(final LoadGraphWith.GraphData graphData) {
            if (graphData != null)
                throw new UnsupportedOperationException("GraphData not supported: " + graphData.name());

            final Configuration conf = getNumberIdManagerConfiguration();
            conf.setProperty(TinkerGraph.GREMLIN_TINKERGRAPH_ALLOW_NULL_PROPERTY_VALUES, true);
            return world.open(conf).traversal();
        }
Enables the storing of {@code null} property values when testing. This is a terminal decorator and shouldn't be
used as an input into another decorator.
tinkergraph-gremlin/src/test/java/org/apache/tinkerpop/gremlin/tinkergraph/TinkerWorld.java