public static Function<? super HttpService, BraveService>
    newDecorator(HttpTracing httpTracing) {
        ensureScopeUsesRequestContext(httpTracing.tracing());
        return service -> new BraveService(service, httpTracing);
    }
Creates a new tracing {@link HttpService} decorator using the specified {@link HttpTracing} instance.
brave/brave6/src/main/java/com/linecorp/armeria/server/brave/BraveService.java