Where are the labels of the Q3DScatter grapph?

I was expecting to see the labels by doing the following:

#include "mainwindow.h"

#include <Q3DScatter>

using namespace QtDataVisualization;

MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) 
{
    Q3DScatter *graph = new Q3DScatter;
    QWidget *widget = QWidget::createWindowContainer(graph);
    setCentralWidget(widget);
    graph->axisX()->setLabels(QStringList{"a", "b", "c"});
}

MainWindow::~MainWindow() {}

But nothing, and I found no method to show/hide labels, so where are the labels?