docs: protected List<MetricDatum> latencyOfClientExecuteTime(Request<?> req, Object response) {
          AWSRequestMetrics m = req.getAWSRequestMetrics();
          TimingInfo root = m.getTimingInfo();
          final String metricName = Field.ClientExecuteTime.name();
          if (root.isEndTimeKnown()) { // being defensive
              List<Dimension> dims = new ArrayList<Dimension>();
              dims.add(new Dimension()
                      .withName(Dimensions.MetricType.name())
                      .withValue(metricName));
              // request type specific
              dims.add(new Dimension()
                      .withName(Dimensions.RequestType.name())
                      .withValue(requestType(req)));
              MetricDatum datum = new MetricDatum()
                  .withMetricName(req.getServiceName())
                  .withDimensions(dims)
                  .withUnit(StandardUnit.Milliseconds)
                  .withValue(root.getTimeTakenMillisIfKnown());
              return Collections.singletonList(datum);
          }
          return Collections.emptyList();
      }