@Test
        @FeatureRequirement(featureClass = Graph.Features.VertexFeatures.class, feature = Graph.Features.VertexFeatures.FEATURE_ADD_VERTICES)
        public void shouldHaveExceptionConsistencyWhenUsingSystemVertexLabel() {
            final String label = Graph.Hidden.hide("systemLabel");
            try {
                graph.addVertex(T.label, label);
                fail("Call to Graph.addVertex() should throw an exception when label is a system key");
            } catch (Exception ex) {
                validateException(Element.Exceptions.labelCanNotBeAHiddenKey(label), ex);
            }
        }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/structure/VertexTest.java