private static void assertCommonB(final Traversal<Vertex, Map<String, Long>> traversal) {
        final Map<String, Long> map = traversal.next();
        assertEquals(map.size(), 2);
        assertEquals(3l, map.get("lop").longValue());
        assertEquals(1l, map.get("ripple").longValue());
        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