@Override
    public void registerClasses(final Kryo kryo) {
        registerClasses(kryo, Collections.emptyMap(), Collections.emptySet());
    }
A spark.kryo.registrator implementation that installs TinkerPop types.
This is intended for use with spark.serializer=KryoSerializer, not GryoSerializer.
spark-gremlin/src/main/java/org/apache/tinkerpop/gremlin/spark/structure/io/gryo/GryoRegistrator.java