@Override
    protected void getReceivers(GeometryList lightReceivers) {
        lightReceivers.clear();
        Camera[] cameras = new Camera[1];
        cameras[0] = shadowCam;
        for (Spatial scene : viewPort.getScenes()) {
            ShadowUtil.getLitGeometriesInViewPort(scene, viewPort.getCamera(), cameras, RenderQueue.ShadowMode.Receive, lightReceivers);
        }
    }
Sets the light to use to cast shadows

@param light a SpotLight
jme3-core/src/main/java/com/jme3/shadow/SpotLightShadowRenderer.java