@Override
  public void close() {
    long closeStartTime = System.currentTimeMillis();
    discardResponses();
    logger.trace("Closed AsyncResponseHandler");
    metrics.responseHandlerCloseTimeInMs.update(System.currentTimeMillis() - closeStartTime);
  }
Creates a AsyncResponseHandler that can handle responses.
@param metrics the {@link RequestResponseHandlerMetrics} instance to use to track metrics.
ambry-rest/src/main/java/com/github/ambry/rest/AsyncRequestResponseHandler.java