private static void assertCommonC(final Traversal<Vertex, Map<Object, Long>> traversal) {
        final Map<Object, Long> map = traversal.next();
        assertEquals(0, map.size());
        assertFalse(traversal.hasNext());
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
@author Stephen Mallette (http://stephen.genoprime.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/sideEffect/GroupCountTest.java