Can't add articulation root

[hijimasa]

I think that a joint can not set to the articulation root.
In this post, the articulation root is set to the root link.

Enhancements to URDF Importer Articulation in Version 2023.1.1 Ensure Consistent Root Link Designation for Improved Simulation Accuracy

Up until version 2023.1.0, the URDF importer assigned the ArticulationRootAPI to the top-level prim of the articulation structure. The root link was then identified by PhysX through an analysis of the kinematic tree. This practice was revised in version 2023.1.1, whereby the ArticulationRootAPI is now directly associated with the actual root link. For example, in version 2023.1.0, when importing a Franka URDF, the ArticulationRootAPI would be placed on /World/Franka, and PhysX might designate an…

Is /firefighter/base already set to the articulation root?