public default GraphTraversalSource traversal(final Graph graph) {
        return graph.traversal();
    }
Create a {@link GraphTraversalSource} from a {@link Graph} instance.  The default implementation does not
use {@link GraphComputer} so providers should override as necessary if their implementation is testing
something that requires a different engine type, like {@link GraphComputer}.
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/GraphProvider.java