private static void maybeRemoveContentLength(int statusCode,
                                                 io.netty.handler.codec.http.HttpHeaders outHeaders) {
        if (statusCode == 304) {
            // 304 response can have the "content-length" header when it is a response to a conditional
            // GET request. See https://datatracker.ietf.org/doc/html/rfc7230#section-3.3.2
        } else {
            outHeaders.remove(HttpHeaderNames.CONTENT_LENGTH);
        }
    }
The ID of the last request whose response headers is written.
core/src/main/java/com/linecorp/armeria/server/ServerHttp1ObjectEncoder.java