code: func validateOnlyAddedTolerations(newTolerations []core.Toleration, oldTolerations []core.Toleration, fldPath *field.Path) field.ErrorList {
  	allErrs := field.ErrorList{}
  	for _, old := range oldTolerations {
  		found := false
  		old.TolerationSeconds = nil
  		for _, new := range newTolerations {
  			new.TolerationSeconds = nil
  			if reflect.DeepEqual(old, new) {
  				found = true
  				break
  			}
  		}
  		if !found {
  			allErrs = append(allErrs, field.Forbidden(fldPath, "existing toleration can not be modified except its tolerationSeconds"))
  			return allErrs
  		}
  	}
  
  	allErrs = append(allErrs, ValidateTolerations(newTolerations, fldPath)...)
  	return allErrs
  }
docs: // validateOnlyAddedTolerations validates updated pod tolerations.