code: @Override
      public List<Metric> transform(QueryContext context, List<Metric> metrics) {
          SystemAssert.requireArgument(metrics != null, "Cannot transform null metric/metrics");
          if (metrics.isEmpty()) {
              return metrics;
          }
  
          Transform unionTransform = new MetricUnionTransform(new UnionValueUnionReducer());
  
          return unionTransform.transform(null, metrics);
      }
docs: ~ Methods **************************************************************************************************************************************