code: public void cancel(ResponseCallback responseCallback) {
      // To avoid creating an extra message, we adopt the convention that writing the callback
      // directly means cancellation
      writeCoalescer.writeAndFlush(channel, responseCallback).addListener(UncaughtExceptions::log);
    }
docs: Cancels a callback, indicating that the client that wrote it is no longer interested in the
  answer.
  
  <p>Note that this does not cancel the request server-side (but might in the future if Cassandra
  supports it).