public OpenConfigComponentHandler addConfig(OpenConfigConfigOfComponentHandler config) {
        modelObject.config(config.getModelObject());
        return this;
    }
@Test
    public void testAddConfig() {
        // test Handler
        OpenConfigComponentHandler component = new OpenConfigComponentHandler("name", parent);

        // call addConfig
        OpenConfigConfigOfComponentHandler config = new OpenConfigConfigOfComponentHandler(component);

        // expected ModelObject
        DefaultComponent modelObject = new DefaultComponent();
        modelObject.name("name");
        DefaultConfig con = new DefaultConfig();
        modelObject.config(con);

        assertEquals("[NG]addConfig:ModelObject(Config added) is not an expected one.\n",
                     modelObject, component.getModelObject());
    }