@Override
    public void addView(View child, int index) {
        // This view only accepts ARScene and VrView children!
        if (!(child instanceof VRTARScene) && !(child instanceof ViroView)) {
            throw new IllegalArgumentException("Attempted to add a non-ARScene element ["
                    + child.getClass().getSimpleName() + "] to ARSceneNavigator!");
        }
        super.addView(child, index);
    }
ARSceneNavigator manages the various AR scenes that a Viro App can navigate between.
android/viro_bridge/src/main/java/com/viromedia/bridge/component/VRTARSceneNavigator.java