WebClient Spring put请求返回值​；“始终”；空"；

我无法通过Spring WebClient获得PUT请求。对于我的“患者”实体的属性，“null”总是被传递并写入数据库。我做错了什么？（put（）直接作用于我的RESTful服务。没关系。）

控制器

@Autowired
    WebClient webClient;

    @PutMapping(path = "/client/{id}")
    public Mono<Patient> update(Patient patient) {
        return webClient.put()
                .uri("/patient/" + patient.getId())
                .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE)
                .header(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON_VALUE).body(Mono.just(patient), Patient.class)
                .retrieve().bodyToMono(Patient.class);
    }

@Configuration
public class WebClientConfig {

    @Bean
    public WebClient getWebClient() {
        WebClient webClient = WebClient.builder().baseUrl("http://localhost:8080")
                .defaultCookie("cookieKey", "cookieValue")
                .defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE).build();
        return webClient;
    }

}

{
    "id": 29,
    "nachname": null,
    "vorname": null,
    "geburtsdatum": null
}