com.unity.perception/com.unity.perception/Editor/Randomization/Uxml/ParameterElement.uxml

<UXML xmlns="UnityEngine.UIElements" xmlns:editor="UnityEditor.UIElements">
    <VisualElement>
        <Style src="../Uss/ParameterStyles.uss"/>
        <VisualElement name="properties"/>
    </VisualElement>
</UXML>