@Override
    public String toString() {
        return StringFactory.stepString(this, this.targetVertexFilter.get(), this.edgeTraversal.get(),
                this.distanceTraversal.get(), this.maxDistance, this.includeEdges, new GraphFilter(this.computer));
    }
@author Daniel Kuppitz (http://gremlin.guru)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/computer/traversal/step/map/ShortestPathVertexProgramStep.java