How to disable include file in launch.xml file

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Hi,

I'm playing with ros2 autoware,

in autoware.launch.xml, it includes

  <group if="$(var launch_perception)">
    <include file="$(find-pkg-share autoware_launch)/launch/components/tier4_perception_component.launch.xml"/>
  </group>

By my understanding, if the var of launch_perception is false then the file of tier4_perception_component.launch.xml will not be included.

But during my test, I always have an error of required argument from tier4_perception_component.launch.xml and its included xml file.

My question:

it seems that even when <group if=false>, the xml file will still be loaded to check the required arguments, is it by design?