@Override
    public DefaultSparqlTraversal<S, E> clone() {
        return (DefaultSparqlTraversal<S, E>) super.clone();
    }
@author Stephen Mallette (http://stephen.genoprime.com)
sparql-gremlin/src/main/java/org/apache/tinkerpop/gremlin/sparql/process/traversal/dsl/sparql/DefaultSparqlTraversal.java