Configure spring boot to redirect 404 to a single page app [duplicate]

This is the full Spring Boot 2.0 example:

@Configuration
public class WebApplicationConfig implements WebMvcConfigurer {

@Override
public void addViewControllers(ViewControllerRegistry registry) {
    registry.addViewController("/notFound").setViewName("forward:/index.html");
}


@Bean
public WebServerFactoryCustomizer<ConfigurableServletWebServerFactory> containerCustomizer() {
    return container -> {
        container.addErrorPages(new ErrorPage(HttpStatus.NOT_FOUND,
                "/notFound"));
    };
  }

}