JointPositionController gui doesn't work if JointPositionController system plugin's topic is set.

[ijnek]

Environment

• OS Version: Ubuntu 22.04 Jammy
• Source or binary build? Binary build (ign-gazebo6)

Description

• Expected behavior: Joint Position Controller GUI should work even if the <topic> tag for the JointPositionController system is set to something else but the default.
• Actual behavior: Joint Position Controller GUI relies on the default topic ("/model/" + modelName + "/joint/" + jointName + "/0/cmd_pos")

How to improve?

I don't know what the best way to go about improving this is. Can the Joint Position Controller GUI determine the topics by looking at the robot's model?