Forcing a new OSG RenderBin from a plugin

void MyNode::traverse(osg::NodeVisitor& nv)
{
    if ( nv.getVisitorType() == nv.CULL_VISITOR )
    {
        osgUtil::CullVisitor* cv = dynamic_cast<osgUtil::CullVisitor*>(&nv);

        osg::ref_ptr<osgUtil::RenderBin> newBin;

        osgUtil::RenderBin* bin = cv->getCurrentRenderBin();
        osgUtil::RenderBin* parentBin = bin->getParent();

        if ( parentBin )
        {
            // If a parent bin exists, "allocate" the first unused bin number from its list of children
            // and use that to force the creation of a new traversal-order bin:
            int newBinNumber = parentBin->getRenderBinList().rbegin()->first + 1;
            newBin = parentBin->find_or_insert(newBinNumber, "TraversalOrderBin");
        }
        else
        {
            // If there is no parent, fall back on the stage and allocate a new child bin there:
            int newBinNumber = bin->getStage()->getBinNum() + 1;
            newBin = bin->getStage()->find_or_insert(newBinNumber, "TraversalOrderBin");
        }

        // activate our new bin and traverse:
        cv->setCurrentRenderBin( newBin.get() );

        osg::Group::traverse(nv);

        // restore the previous bin:
        cv->setCurrentRenderBin( bin );
    }
    else
    {
        osg::Group::traverse( nv );
    }
}