如何根据Flux对象是否有元素在webflux中返回不同的响应？

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

@RestController
public class MyController {

    @GetMapping("/data")
    public Mono<ResponseEntity<String>> getData() {
        Flux<String> data = // 从某个数据源获取数据，返回一个Flux对象
        return data.collectList()
                .flatMap(list -> {
                    if (list.isEmpty()) {
                        return Mono.just(ResponseEntity.notFound().build());
                    } else {
                        return Mono.just(ResponseEntity.ok("Data found"));
                    }
                });
    }
}

@Configuration
@EnableWebFlux
public class WebConfig implements WebFluxConfigurer {

    @Override
    public void configureRouter(RouterFunction<ServerResponse> routerFunction) {
        routerFunction.route(GET("/data"), this::getData);
    }

    private Mono<ServerResponse> getData(ServerRequest request) {
        MyController controller = new MyController();
        return controller.getData();
    }
}