为什么我的restemplate ClientHttpRequestInterceptor没有被调用?

我想使用拦截器将授权头添加到通过rest模板发出的每个请求中。我是这样做的:

public FirebaseCloudMessagingRestTemplate(@Autowired RestTemplateBuilder builder, @Value("fcm.server-key") String serverKey) {
    builder.additionalInterceptors(new ClientHttpRequestInterceptor() {
        @Override
        public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution) throws IOException {
            request.getHeaders().add("Authorization", "key=" + serverKey);
            System.out.println(request.getHeaders());
            return execution.execute(request, body);
        }
    });
    this.restTemplate = builder.build();
}

  DownstreamHttpMessageResponse response = restTemplate.postForObject(SEND_ENDPOINT, request, DownstreamHttpMessageResponse.class);

拦截器未被调用(Iv在其中放置断点,但它未触发)。发出请求并返回明显缺失的身份验证密钥响应。为什么我的拦截器没有被调用?