Base Motion constraints in Isaac Sim

Is there a way to restrict the free floating base motion to certain directions?
Currently I am using
omni.isaac.urdf in order to import a robot urdf from a python script.
_urdf.ImportConfig() seems to only support a boolean specifying whether the base is fixed or not.

Is it possible to restrict the base motion to xy plane for example using this setup?

You can add dummy links and joints to the URDF before importing it into Isaac Sim.