com.unity.uiextensions/Runtime/Scripts/Utilities/NonDrawingGraphic.cs

/// Credit Slipp Douglas Thompson 
/// Sourced from - https://gist.github.com/capnslipp/349c18283f2fea316369

namespace UnityEngine.UI.Extensions
{
    /// A concrete subclass of the Unity UI `Graphic` class that just skips drawing.
    /// Useful for providing a raycast target without actually drawing anything.
    [AddComponentMenu("Layout/Extensions/NonDrawingGraphic")]
    [RequireComponent(typeof(CanvasRenderer))]
    public class NonDrawingGraphic : MaskableGraphic
    {
        public override void SetMaterialDirty() { return; }
        public override void SetVerticesDirty() { return; }

        /// Probably not necessary since the chain of calls `Rebuild()`->`UpdateGeometry()`->`DoMeshGeneration()`->`OnPopulateMesh()` won't happen; so here really just as a fail-safe.
        protected override void OnPopulateMesh(VertexHelper vh)
        {
            vh.Clear();
            return;
        }
    }
}