code: public Observable<OperationStatusResponseInner> reimageAllAsync(String resourceGroupName, String vmScaleSetName) {
          return reimageAllWithServiceResponseAsync(resourceGroupName, vmScaleSetName).map(new Func1<ServiceResponse<OperationStatusResponseInner>, OperationStatusResponseInner>() {
              @Override
              public OperationStatusResponseInner call(ServiceResponse<OperationStatusResponseInner> response) {
                  return response.body();
              }
          });
      }
docs: Reimages all the disks ( including data disks ) in the virtual machines in a VM scale set. This operation is only supported for managed disks.
  
  @param resourceGroupName The name of the resource group.
  @param vmScaleSetName The name of the VM scale set.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable for the request