@Override
    protected Iterator<Vertex> flatMap(final Traverser.Admin<Edge> traverser) {
        return traverser.get().vertices(this.direction);
    }
@author Marko A. Rodriguez (http://markorodriguez.com)
gremlin-core/src/main/java/org/apache/tinkerpop/gremlin/process/traversal/step/map/EdgeVertexStep.java