@Override
        protected boolean isContentAlwaysEmpty(@SuppressWarnings("unused") HttpResponse msg) {
            method = queue.poll();
            return HttpMethod.HEAD.equals(method) || super.isContentAlwaysEmpty(msg);
        }
Upgrades to another protocol from HTTP. Removes the {@link HttpRequestDecoder} and
{@link HttpResponseEncoder} from the pipeline.
core/src/main/java/com/linecorp/armeria/server/HttpServerCodec.java