private static void validateSubScene(Spatial scene) {
        scene.checkCulling(DUMMY_CAM);

        Set<MatParamOverride> actualOverrides = new HashSet<>();
        for (MatParamOverride override : scene.getWorldMatParamOverrides()) {
            actualOverrides.add(override);
        }

        Set<MatParamOverride> expectedOverrides = new HashSet<>();
        Spatial current = scene;
        while (current != null) {
            for (MatParamOverride override : current.getLocalMatParamOverrides()) {
                expectedOverrides.add(override);
            }
            current = current.getParent();
        }

        assertEquals("For " + scene, expectedOverrides, actualOverrides);
    }
A private constructor to inhibit instantiation of this class.
jme3-core/src/test/java/com/jme3/scene/MPOTestUtils.java