@Override
        public void onComplete() {
            if (!writer.isOpen()) {
                return;
            }
            if (!trailers.isEmpty()) {
                if (!writer.tryWrite(trailers)) {
                    return;
                }
            }
            writer.close();
        }
A {@link Subscriber} implementation which writes a streaming response with the contents converted from
the objects published from a publisher.
core/src/main/java/com/linecorp/armeria/internal/server/ResponseConversionUtil.java