anchor.diff:  ==>PartitionGraphStrategy
   gremlin> sg = new StrategyWrappedGraph(g)
   ==>strategywrappedgraph[tinkergraph[vertices:0 edges:0]]
  -gremlin> sg.strategy().setGraphStrategy(strategy)
  +gremlin> sg.getStrategy().setGraphStrategy(strategy)
   ==>null
   ----
   
  
positive.code: ==>neo4jgraph[EmbeddedGraphDatabase [/tmp/neo4j]]
  gremlin> swg = new StrategyWrappedGraph(g)
  ==>defaultgraphstrategy[neo4jgraph[EmbeddedGraphDatabase [/tmp/neo4j]]]
  gremlin> swg.strategy().setGraphStrategy(IdGraphStrategy.build("idKey").create())
  ==>null
  gremlin> swg.addVertex(id,"42a").id()
  ==>42a
  
negative.code: 
  GraphStrategy strategy = new SubgraphStrategy(vertexCriterion, edgeCriterion);
  StrategyWrappedGraph sg = new StrategyWrappedGraph(g);
  sg.getStrategy().setGraphStrategy(strategy);
  
  // all vertices are here
  System.out.println("" + sg.V().count() + " of " + g.V().count() + " vertices");
  