code: public OperationStatusResponseInner beginReimage(String resourceGroupName, String vmScaleSetName, String instanceId) {
          return beginReimageWithServiceResponseAsync(resourceGroupName, vmScaleSetName, instanceId).toBlocking().single().body();
      }
docs: Reimages (upgrade the operating system) a specific virtual machine in a VM scale set.
  
  @param resourceGroupName The name of the resource group.
  @param vmScaleSetName The name of the VM scale set.
  @param instanceId The instance ID of the virtual machine.
  @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.