public CreateBookingCommandHandler(
     IUserRepository userRepository,
     IAvailableCarRepository availableCarRepository,
     IBookingRepository bookingRepository
     )
 {
     this.userRepository         = userRepository ?? throw new ArgumentNullException(nameof(userRepository));
     this.availableCarRepository = availableCarRepository ?? throw new ArgumentNullException(nameof(availableCarRepository));
     this.bookingRepository      = bookingRepository ?? throw new ArgumentNullException(nameof(bookingRepository));
 }
 public AvailableCarAppService(IAvailableCarRepository availableCarRepository)
 {
     this.availableCarRepository = availableCarRepository ?? throw new ArgumentNullException(nameof(availableCarRepository));
 }