@Bean
public RouterFunction<ServerResponse> routes() {
    return  route()
            .path("/student", builder -> builder
                    .GET("/output/{id}", accept(APPLICATION_JSON), req -> ok().contentType(MediaType.APPLICATION_JSON)
                            .body(Mono.justOrEmpty(studentService.getPayload(req.pathVariable("id"))), String.class)))
            .build();
}

There was an unexpected error (type=Internal Server Error, status=500).
Not allowed to capture 'id' twice in the same pattern