code: public Observable<ServiceResponse<Void>> resizeWithServiceResponseAsync(String resourceGroupName, String clusterName) {
          if (this.client.subscriptionId() == null) {
              throw new IllegalArgumentException("Parameter this.client.subscriptionId() is required and cannot be null.");
          }
          if (resourceGroupName == null) {
              throw new IllegalArgumentException("Parameter resourceGroupName is required and cannot be null.");
          }
          if (clusterName == null) {
              throw new IllegalArgumentException("Parameter clusterName is required and cannot be null.");
          }
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          final String roleName = "workernode";
          final Integer targetInstanceCount = null;
          ClusterResizeParameters parameters = new ClusterResizeParameters();
          parameters.withTargetInstanceCount(null);
          Observable<Response<ResponseBody>> observable = service.resize(this.client.subscriptionId(), resourceGroupName, clusterName, roleName, this.client.apiVersion(), this.client.acceptLanguage(), parameters, this.client.userAgent());
          return client.getAzureClient().getPostOrDeleteResultAsync(observable, new TypeToken<Void>() { }.getType());
      }
docs: Resizes the specified HDInsight cluster to the specified size.
  
  @param resourceGroupName The name of the resource group.
  @param clusterName The name of the cluster.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable for the request