code: func DropDisabledFields(resSpec *api.ResourceQuotaSpec, oldResSpec *api.ResourceQuotaSpec) {
  	if !utilfeature.DefaultFeatureGate.Enabled(features.ResourceQuotaScopeSelectors) && !resourceQuotaScopeSelectorInUse(oldResSpec) {
  		resSpec.ScopeSelector = nil
  	}
  }
docs: // DropDisabledFields removes disabled fields from the ResourceQuota spec.
  // This should be called from PrepareForCreate/PrepareForUpdate for all resources containing a ResourceQuota spec.