code: func ValidateControllerRevisionUpdate(newHistory, oldHistory *apps.ControllerRevision) field.ErrorList {
  	errs := field.ErrorList{}
  
  	errs = append(errs, apivalidation.ValidateObjectMetaUpdate(&newHistory.ObjectMeta, &oldHistory.ObjectMeta, field.NewPath("metadata"))...)
  	errs = append(errs, ValidateControllerRevision(newHistory)...)
  	errs = append(errs, apivalidation.ValidateImmutableField(newHistory.Data, oldHistory.Data, field.NewPath("data"))...)
  	return errs
  }
docs: // ValidateControllerRevisionUpdate collects errors pertaining to the mutation of an ControllerRevision Object. If the
  // returned ErrorList is empty the update operation is valid. Any mutation to the ControllerRevision's Data or Revision
  // is considered to be invalid.