如何让Spring的WebFlux发出响应

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

@RestController
public class MyController {
    @GetMapping("/hello")
    public Mono<String> sayHello() {
        return Mono.just("Hello, World!");
    }
}

@Configuration
@EnableWebFlux
public class WebConfig implements WebFluxConfigurer {
    @Override
    public void configureRouter(RouterFunction<ServerResponse> routerFunction) {
        routerFunction.route(GET("/hello"), this::handleHelloRequest);
    }

    private Mono<ServerResponse> handleHelloRequest(ServerRequest request) {
        return ServerResponse.ok().bodyValue("Hello, World!");
    }
}

@SpringBootApplication
public class MyApp {
    public static void main(String[] args) {
        SpringApplication.run(MyApp.class, args);
    }
}