Nullable arguments will be added to the `introspect` datastructures in a future change.
PiperOrigin-RevId: 789350522
Change-Id: I0bfd12fab5121f94b937264570f907593b63cf64
For the MJCF -> USD plugin, and I suspect other usecases for user values, it's necessary to give ownership of the object to Mujoco. However since they get type erased, we can't clean up the data automatically for the user. Instead this allows c++ clients to provide a cleanup function with their data.
PiperOrigin-RevId: 756832010
Change-Id: I80b8e7822e1a0e399a0d19dcaa57ee69b3ccc16a