@Test(expected = IllegalStateException.class)
    public void shouldFailWhenUsingOptionAndCardinalityArgumentWithoutMergeV() {
        final Map<Object, Object> m = new HashMap<Object,Object>() {{
            put("k", 1);
        }};
        g.mergeE(new HashMap<>()).option(Merge.onMatch, m, VertexProperty.Cardinality.list);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-core/src/test/java/org/apache/tinkerpop/gremlin/process/traversal/dsl/graph/GraphTraversalTest.java