@Override
    public SubgraphStep clone() {
        final SubgraphStep clone = (SubgraphStep) super.clone();
        this.subgraph = null;
        return clone;
    }
A side-effect step that produces an edge induced subgraph.

@author Stephen Mallette (http://stephen.genoprime.com)
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/sideEffect/SubgraphStep.java