docs: public DescribeSpotFleetInstancesResult withActiveInstances(ActiveInstance... activeInstances) {
          if (this.activeInstances == null) {
              setActiveInstances(new com.amazonaws.internal.SdkInternalList<ActiveInstance>(activeInstances.length));
          }
          for (ActiveInstance ele : activeInstances) {
              this.activeInstances.add(ele);
          }
          return this;
      }