TrainCreateChangeRequest

{
    "customOrderId": "EXT-TRAIN-CHANGE-001",
    "seatClassId": "yidengzuo",
    "passengerIds": [
        10001
    ],
    "shoppingId": "train_change_shop_01J2X9",
    "journeyId": "train_journey_G3_20260721",
    "returnJourneyId": "train_journey_G4_20260726",
    "callbackUrl": "https://buyer.example.com/callbacks/train/change",
    "autoConfirm": false,
    "preference": {
        "chooseSeats": "1A1D",
        "chooseBeds": "123",
        "allowStanding": false,
        "carNumber": 8
    },
    "returnPreference": {
        "chooseSeats": "1A1D",
        "chooseBeds": "123",
        "allowStanding": false,
        "carNumber": 8
    }
}