assets/playground/open_cabinet/mjcf/barrier.xml

<mujoco model="barrier">
    <worldbody>
        <geom type="box" name="barrier_geom"
            pos="0.0 0 0"
            size="0.01 1 1"
            condim="3"
            friction="1 .03 .003"
            rgba="0 1 0 0.2"
            contype="2"
            conaffinity="1"
            solref="0.01 1" />
    </worldbody>
</mujoco>