Using multiple conveyor belts within one world

[RobinHeitz]

Hi,

When adding multiple conveyor belts in a world file (like in your conveyorbelt.world file), I can change the name of the conveyor belt, but not change the underlying namespace, so on launch it will then fail, because it adds no namespace like /conv1/CONVEYOR to the provided service to start/ stop the belt.

Is there are working example on inserting/ overwriting ros and gazebo namespace from the world file?