Can't setTextureCoordinatesTransform easily on a QQuickFramebufferObject derived class

QSGNode *MyQQuickFramebufferObject::updatePaintNode(QSGNode *node, QQuickItem::UpdatePaintNodeData *nodeData)
{
    if (!node) {
        node = QQuickFramebufferObject::updatePaintNode(node, nodeData);
        QSGSimpleTextureNode *n = static_cast<QSGSimpleTextureNode *>(node);
        if (n)
            n->setTextureCoordinatesTransform(QSGSimpleTextureNode::MirrorVertically);
        return node;
    }
    return QQuickFramebufferObject::updatePaintNode(node, nodeData);
}