docs: public void sendBuffer(final HttpResponseStatus status,
                            final ChannelBuffer buf,
                            final String contentType) {
      if (!chan.isConnected()) {
        if(stats != null) {
          stats.markSendFailed();
        }
        done();
        return;
      }
      response.headers().set(HttpHeaders.Names.CONTENT_TYPE, contentType);
  
      // TODO(tsuna): Server, X-Backend, etc. headers.
      // only reset the status if we have the default status, otherwise the user
      // already set it
      response.setStatus(status);
      response.setContent(buf);
      final boolean keepalive = HttpHeaders.isKeepAlive(request);
      if (keepalive) {
        HttpHeaders.setContentLength(response, buf.readableBytes());
      }
      final ChannelFuture future = chan.write(response);
      if (stats != null) {
        future.addListener(new SendSuccess());
      }
      if (!keepalive) {
        future.addListener(ChannelFutureListener.CLOSE);
      }
      done();
    }