Spring catch all route for index.html

Since my react app could use the root as forward target this ended up working for me

@Configuration
public class WebConfiguration extends WebMvcConfigurerAdapter {

  @Override
  public void addViewControllers(ViewControllerRegistry registry) {
      registry.addViewController("/{spring:\\w+}")
            .setViewName("forward:/");
      registry.addViewController("/**/{spring:\\w+}")
            .setViewName("forward:/");
      registry.addViewController("/{spring:\\w+}/**{spring:?!(\\.js|\\.css)$}")
            .setViewName("forward:/");
  }
}

To be honest I have no idea why it has to be exactly in this specific format to avoid infinite forwarding loop.