public OpenConfigConfigOfChannelHandler addIndex(Integer index) {
        modelObject.index(index);
        return this;
    }
@Test
    public void testAddIndex() {
        // test Handler
        OpenConfigConfigOfChannelHandler config = new OpenConfigConfigOfChannelHandler(parent);

        // call addIndex
        config.addIndex(2);

        // expected ModelObject
        DefaultConfig modelObject = new DefaultConfig();
        modelObject.index(2);

        assertEquals("[NG]addIndex:ModelObject(Index added) is not an expected one.\n",
                     modelObject, config.getModelObject());
    }