public IReadOnlyList <AirTariff> GetAirTariffs() { if (Tariffs == null) { return(new List <AirTariff>()); } return(Tariffs.OfType <AirTariff>().ToList()); }
public IEnumerable <AirTariff> GetAirTariffs() { if (Tariffs == null) { return(Enumerable.Empty <AirTariff>()); } return(Tariffs.OfType <AirTariff>()); }