docs: private RequestMetricCollector findRequestMetricCollector(RequestConfig requestConfig) {
          RequestMetricCollector reqLevelMetricsCollector = requestConfig
                  .getRequestMetricsCollector();
          if (reqLevelMetricsCollector != null) {
              return reqLevelMetricsCollector;
          } else if (clientLevelMetricCollector != null) {
              return clientLevelMetricCollector;
          } else {
              return AwsSdkMetrics.getRequestMetricCollector();
          }
      }