docs: public GetUsagePlanResult withApiStages(ApiStage... apiStages) {
          if (this.apiStages == null) {
              setApiStages(new java.util.ArrayList<ApiStage>(apiStages.length));
          }
          for (ApiStage ele : apiStages) {
              this.apiStages.add(ele);
          }
          return this;
      }