How to set Model:geometry from C++?

[Tom asso]

Looking at QtQuick 3D Model QML type, it has a "geometry" property that can be used to specify custom geometry for the model (used instead of the "source" property that specifies a mesh). The geometry property has type Geometry. How can I load the geometry data in C++ and then specify it as the Model:geometry property? Does anyone know of a working example?
Thanks!