code: public OperationStatusResponseInner updateInstances(String resourceGroupName, String vmScaleSetName, List<String> instanceIds) {
          return updateInstancesWithServiceResponseAsync(resourceGroupName, vmScaleSetName, instanceIds).toBlocking().last().body();
      }
docs: Upgrades one or more virtual machines to the latest SKU set in the VM scale set model.
  
  @param resourceGroupName The name of the resource group.
  @param vmScaleSetName The name of the VM scale set.
  @param instanceIds The virtual machine scale set instance ids.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws CloudException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the OperationStatusResponseInner object if successful.