public FlightEndpoint(FlightTicket ticket, IReadOnlyList <FlightLocation> locations)
 {
     _ticket    = ticket;
     _locations = locations;
 }
 internal FlightEndpoint(Protocol.FlightEndpoint flightEndpoint)
 {
     _ticket    = new FlightTicket(flightEndpoint.Ticket);
     _locations = flightEndpoint.Location.Select(x => new FlightLocation(x)).ToList();
 }