code: func (s *SearchService) DocvalueFieldsWithFormat(docvalueFields ...DocvalueField) *SearchService {
  	s.searchSource = s.searchSource.DocvalueFieldsWithFormat(docvalueFields...)
  	return s
  }
docs: // DocvalueFieldsWithFormat adds one or more fields to load from the field data cache
  // and return as part of the search.