public Route mappedRoute() {
        return mappedRoute;
    }
Returns the {@link Route} whose prefix is removed when an {@link HttpServiceWithRoutes} is added
via {@link ServerBuilder#serviceUnder(String, HttpService)}.
For example, in the following code, the path of the {@link #mappedRoute()} will be ({@code "/bar"})
whereas the path of the {@link #route()} will be ({@code "/foo/bar"}):
<pre>{@code
> HttpServiceWithRoutes serviceWithRoutes = new HttpServiceWithRoutes() {
>     @Override
>     public HttpResponse serve(ServiceRequestContext ctx, HttpRequest req) { ... }
>
>     @Override
>     public Set<Route> routes() {
>         return Set.of(Route.builder().path("/bar").build());
>     }
> };
>
> Server.builder()
>       .serviceUnder("/foo", serviceWithRoutes)
>       .build();
}</pre>
If the service is not an {@link HttpServiceWithRoutes}, the {@link Route} is the same as
{@link #route()}.
core/src/main/java/com/linecorp/armeria/server/ServiceConfig.java