code: func (s *Scheme) ConvertFieldLabel(gvk schema.GroupVersionKind, label, value string) (string, string, error) {
  	conversionFunc, ok := s.fieldLabelConversionFuncs[gvk]
  	if !ok {
  		return DefaultMetaV1FieldSelectorConversion(label, value)
  	}
  	return conversionFunc(label, value)
  }
docs: // ConvertFieldLabel alters the given field label and value for an kind field selector from
  // versioned representation to an unversioned one or returns an error.