public void setCustomRenderer(Class<? extends JmeContext> clazz) {
        put("Renderer", "CUSTOM" + clazz.getName());
    }
Set a custom graphics renderer to use. The class should implement
the {@link JmeContext} interface.
@param clazz The custom context class.
(Default: not set)
jme3-core/src/main/java/com/jme3/system/AppSettings.java