@Nullable
    default Boolean reportMaskedRoutes() {
        return null;
    }
Returns whether to log a warning if a {@link ServiceWithRoutes} is added to a {@link ServerBuilder}
using the methods that requires a path pattern, such as
{@link ServerBuilder#service(String, HttpService)}. For example, the following code will mask the
returned route ({@code "/foo"}) in favor of the specified route ({@code "/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("/foo").build());
>     }
> };
>
> Server.builder()
>       .service("/bar", serviceWithRoutes)
>       .build();
}</pre>
core/src/main/java/com/linecorp/armeria/common/FlagsProvider.java