... Python OpenStudio bindings: surface.vertices() -> tuple?

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To OpenStudio SDK devs working with Python bindings ...

As a Python-SDK training exercise, I'm in the process of converting existing Ruby gems to Python packages/modules. It's going fairly smoothly (e.g. Ruby vs Python unit test results are lining up). Yet I'm hitting something weird when I try the following (here, using the interactive Python interpreter):

vtx = openstudio.Point3dVector()
vtx.append(openstudio.Point3d( 0, 0,10))
vtx.append(openstudio.Point3d( 0, 0, 0))
vtx.append(openstudio.Point3d(10, 0, 0))
vtx.append(openstudio.Point3d(10, 0,10))

model = openstudio.model.Model()
surface = openstudio.model.Surface(vtx, model)
print(surface.vertices().__class__.__name__)

>>> tuple

Tuple? Shouldn't it be an openstudio.model.Point3dVector? I can work around this, e.g. converting to a list, or generating a new Point3dVector (point by point). But it would be better to stick to SDK documented return types. This is the first snag of this nature I've come across.

Is this a bug, or expected behaviour? Am I missing something really obvious (documented somewhere)? I haven't found anything on UMH or the OpenStudio GitHub repo. Working with SDK v3.9.0 & Python 3.10, BTW.

Thanks in advance,