Optional: If specified, only document property values in this list are returned for matched documents, regardless of any 'return with result' setting on the index level. If the collection is null or empty (default case), 'return with result' settings on the index level is used to control whether document property data are returned in the search result.

public List<string> CustomReturnedProperties { get; set; }

public List<string> CustomReturnedProperties { get; set; }