@Override
        public void cancel() {
            final Subscription s = subscription;
            if (s != null) {
                subscription = null;
                try {
                    s.cancel();
                } finally {
                    releaseCachedItem();
                }
            }
        }
The actual writeSubscriber from the HTTP server adapter.
spring/boot3-webflux-autoconfigure/src/main/java/com/linecorp/armeria/spring/web/reactive/ChannelSendOperator.java