code: public Observable<OperationStatusResponseInner> beginDeleteInstancesAsync(String resourceGroupName, String vmScaleSetName, List<String> instanceIds) {
          return beginDeleteInstancesWithServiceResponseAsync(resourceGroupName, vmScaleSetName, instanceIds).map(new Func1<ServiceResponse<OperationStatusResponseInner>, OperationStatusResponseInner>() {
              @Override
              public OperationStatusResponseInner call(ServiceResponse<OperationStatusResponseInner> response) {
                  return response.body();
              }
          });
      }
docs: Deletes virtual machines in a VM scale set.
  
  @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
  @return the observable to the OperationStatusResponseInner object