public void injectMetrics(RestRequestMetrics restRequestMetrics) {
    if (restRequestMetrics != null) {
      metrics = restRequestMetrics;
    } else {
      throw new IllegalArgumentException("RestRequestMetrics provided cannot be null");
    }
  }
Injects a {@link RestRequestMetrics} that can be used to track the metrics of the {@link RestRequest} that this
instance of RestRequestMetricsTracker is attached to.
@param restRequestMetrics the {@link RestRequestMetrics} instance to use to track the metrics of the
                               {@link RestRequest} that this instance of RestRequestMetricsTracker is attached to.
ambry-api/src/main/java/com/github/ambry/rest/RestRequestMetricsTracker.java