Hi. I am using ROS2 Foxy and Gazebo11 in Ubuntu 20.04. I have a xacro file which I first convert into a urdf file using xacro my_file.urdf.xacro > my_file.urdf, and then convert this urdf file to sdf file using gz sdf -p my_file.urdf > my_file.sdf. I also add <preserveFixedJoint>true</preserveFixedJoint> tag for every fixed joint inside myfile.urdf to prevent merging of links that are connected by fixed joints. However, when I go through the generated sdf file, I find that the link `basefootprintand the jointbasejoint(that joinsbasefootprintandbase_link` via a fixed joint) are missing.

I wanted to know how can I preserve the link base_footprint and the joint base_joint while converting urdf to sdf.