code: func ValidateReplicationControllerUpdate(controller, oldController *core.ReplicationController) field.ErrorList {
  	allErrs := ValidateObjectMetaUpdate(&controller.ObjectMeta, &oldController.ObjectMeta, field.NewPath("metadata"))
  	allErrs = append(allErrs, ValidateReplicationControllerSpec(&controller.Spec, field.NewPath("spec"))...)
  	return allErrs
  }
docs: // ValidateReplicationControllerUpdate tests if required fields in the replication controller are set.