How to serve static assets in Lagom?

Question

I am trying to serve static assets with Lagom. I added a play router using additional routers because play has support for serving assets from public folder.

But I can't use Assets.at function here because it is not static. After compiling code, I also don't see the assets jar, play suppose to create.

public class FileServerRouter implements SimpleRouter {

  private final Router delegate;

  @Inject
  public FileServerRouter(RoutingDsl routingDsl) {
    this.delegate =
        routingDsl
            .GET("/assets/*file")
            .routingTo(
                (request, file) -> {
                  // Assets.at(file);
                  return ok("Serving " + file);
                })
            .build()
            .asScala();
  }

  @Override
  public PartialFunction<RequestHeader, Handler> routes() {
    return delegate.routes();
  }
}

Does anyone know how to use Assets.at with RoutingDsl or any other way to serve static assets with lagom?