@Override
        public MapReduce.NullObject generateFinalResult(final Iterator<KeyValue<MapReduce.NullObject, MapReduce.NullObject>> keyValues) {
            return MapReduce.NullObject.instance();
        }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-test/src/main/java/org/apache/tinkerpop/gremlin/process/computer/GraphComputerTest.java