Duplex model has no subcontexts

[Moult]

I was looking at https://github.com/buildingSMART/Sample-Test-Files/blob/master/IFC%202x3/Duplex%20Apartment/Duplex_A_20110907.ifc and noticed it had no geometric subcontexts (e.g. for body). This means that the geometric context is ambiguous.

It's technically not invalid (though I'd argue perhaps this should be added to the spec?) but it a pretty severe lack of information for geometry.