private void checkIfValidBooking(BookingRequestTo bookingRequestTo) throws BookingException {
        if (bookingRequestTo == null) {
            throw new BookingException("No booking request received.");
        }
        if (bookingRequestTo.getTripId() == null) {
            throw new BookingException("No trip id present in booking request.");
        }
        if (bookingRequestTo.getTravelers() == null || bookingRequestTo.getTravelers().isEmpty()) {
            throw new BookingException("No travelers received with booking request.");
        }
        for (TravelerSummaryTo traveler : bookingRequestTo.getTravelers()) {
            checkIfValidTraveler(traveler);
        }
    }