@Override
    public RouterFunction<ServerResponse> create(String prefix) {
        return RouterFunctions.route(GET(StringUtils.prependIfMissing(prefix, "/")),
            handlerFunction());
    }
@Test
    void create() {
        String prefix = "/topics";
        RouterFunction<ServerResponse> routerFunction = categoriesRouteFactory.create(prefix);
        WebTestClient webClient = getWebTestClient(routerFunction);

        when(categoryFinder.listAsTree())
            .thenReturn(Flux.empty());
        webClient.get()
            .uri(prefix)
            .exchange()
            .expectStatus().isOk();
    }