spring boot configuration default welcome page

@Configuration
@Controller
public class IndexConfig extends WebMvcConfigurerAdapter {

    @Override
    public void addViewControllers(ViewControllerRegistry registry) {
        registry.addViewController("/").setViewName("forward:/index.htm");
        registry.setOrder(Ordered.HIGHEST_PRECEDENCE);
        super.addViewControllers(registry);
    }

    @RequestMapping(value = "/index.htm", method = RequestMethod.GET)
    public ModelAndView index(HttpServletRequest request, HttpServletResponse response) throws IOException {
        ModelAndView view = new ModelAndView();
        view.setViewName("index");
        return view;
    }
}

         It can be split into two classes according to requirements.