code: func ValidateReplicaSetUpdate(rs, oldRs *apps.ReplicaSet) field.ErrorList {
  	allErrs := field.ErrorList{}
  	allErrs = append(allErrs, apivalidation.ValidateObjectMetaUpdate(&rs.ObjectMeta, &oldRs.ObjectMeta, field.NewPath("metadata"))...)
  	allErrs = append(allErrs, ValidateReplicaSetSpec(&rs.Spec, field.NewPath("spec"))...)
  	return allErrs
  }
docs: // ValidateReplicaSetUpdate tests if required fields in the ReplicaSet are set.