QtQuick documentation references private class "QQuickColorGroup"

The private class QQuickColorGroup is referenced here: https://doc-snapshots.qt.io/qt6-6.2/qquickcolorgroup.html and here: https://doc.qt.io/qt-6/qquickcolorgroup.html.

I discovered this while trying to assign a palette created in C++ to a QQuickWindow. I was disappointed to realize that you can't create a QQuickColorGroup in C++ using the public APIs. Was this class intended to be made public in 6.0?