code: func validatePSPFSGroup(fldPath *field.Path, groupOptions *policy.FSGroupStrategyOptions) field.ErrorList {
  	allErrs := field.ErrorList{}
  
  	supportedRules := sets.NewString(
  		string(policy.FSGroupStrategyMustRunAs),
  		string(policy.FSGroupStrategyMayRunAs),
  		string(policy.FSGroupStrategyRunAsAny),
  	)
  	if !supportedRules.Has(string(groupOptions.Rule)) {
  		allErrs = append(allErrs, field.NotSupported(fldPath.Child("rule"), groupOptions.Rule, supportedRules.List()))
  	}
  
  	for idx, rng := range groupOptions.Ranges {
  		allErrs = append(allErrs, validateGroupIDRange(fldPath.Child("ranges").Index(idx), rng)...)
  	}
  	return allErrs
  }
docs: // validatePSPFSGroup validates the FSGroupStrategyOptions fields of the PodSecurityPolicy.