### Question:
VertexGraph extends ElementGraph { protected <V extends Vertex> GraphTraversal update(V vertex) { GraphTraversal traversal = find(vertex); return update(traversal, vertex, Properties::of); } VertexGraph(Graph graph, GraphTraversalSource g); org.apache.tinkerpop.gremlin.structure.Vertex delegate(V vertex); Vertex addVertex(V vertex); Vertex removeVertex(V vertex); void reset();  }### Answer:
@Test public void testUpdateElement() { Person marko = createElement(); vertexGraph.update(traversal, marko, Properties::of); InOrder inOrder = inOrder(traversal); inOrder.verify(traversal, times(1)) .property(should.equals(REPLACE) ? single : list, "locations", "san diego", new Object[] { "startTime", year(1997), "endTime", year(2001)}); inOrder.verify(traversal, times(1)) .property(list, "locations", "santa cruz", new Object[] { "startTime", year(2001), "endTime", year(2004) } ); }