@Override
    protected void setMaterials(List<Material> materials) {
        mMaterials = materials;
        setBackgroundOnSurface();
    }
Override setMaterials() of Node because we don't necessarily always want to use the given
Materials (ie. in the case a backgroundColor is also provided).
android/viro_bridge/src/main/java/com/viromedia/bridge/component/node/VRTFlexView.java