我有一个firebase函数，它返回一个包含时间戳的对象

[{
    startTime: firestore.Timestamp.fromDate(randomDate),
    duration: 45 
}]

在swift中，我有一个表示这些数据的模型

struct AvailabilityTimeSlot: Codable {
    let startTime: Date
    let int: Duration
}

后跟调用函数并对其进行解码的代码

func fetchTimeSlotAvailability(date: Date, groomerId: String,  requestedServices: [Pet: [PetServiceAndPricing]]) async throws -> [AvailabilityTimeSlot] {
    let result = try await Functions.functions().httpsCallable("availableBookingTimeSlots")
        .call([
        "date": date.timeIntervalSince1970,
        "groomerId": groomerId,
        "requestedServices": requestedServices
    ])
    
    return try Firestore.Decoder().decode([AvailabilityTimeSlot].self, from: result.data)
}

返回的数据如下所示

[{
duration = 45;
startTime =         {
    "_nanoseconds" = 341000000;
    "_seconds" = 1673116451;
};]

但我收到解码错误

keyNotFound(TimestampKeys(stringValue: "seconds", intValue: nil), Swift.DecodingError.Context(codingPath: [_JSONKey(stringValue: "Index 0", intValue: 0), CodingKeys(stringValue: "startTime", intValue: nil)], debugDescription: "No value associated with key TimestampKeys(stringValue: \"seconds\", intValue: nil) (\"seconds\").", underlyingError: nil))

从firebase函数接收日期的推荐方法是什么？当使用FireStore阅读数据时，时间戳可以按预期工作，但对于函数则不行