@Test
    @FeatureRequirementSet(FeatureRequirementSet.Package.VERTICES_ONLY)
    public void shouldGenerateDefaultIdOnGraphAddVWithGeneratedCustomId() throws Exception {
        final ElementIdStrategy strategy = ElementIdStrategy.build().idMaker(new ConstantSupplier<>("xxx")).create();
        final GraphTraversalSource sg = create(strategy);
        final Vertex v = sg.addV().property("name", "stephen").property("group", 10).next();
        assertEquals("stephen", v.value("name"));
        assertEquals("xxx", sg.V(v).id().next());
        assertEquals("xxx", sg.V("xxx").id().next());
        assertEquals("xxx", sg.V().has(T.id, "xxx").id().next());
        assertEquals("xxx", sg.V().hasId("xxx").id().next());
        assertEquals("xxx", sg.V().has(T.id, "xxx").has("group", 10).id().next());
        assertEquals("xxx", sg.V().has("group", 10).has(T.id, "xxx").id().next());
    }
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/strategy/decoration/ElementIdStrategyProcessTest.java