当日期项为空时，Moshi无法转换Json

class NullableDateAdapter {
    @FromJson
    @Nullable
    fun fromJson(reader: JsonReader): Date? {
        if (reader.peek() == JsonReader.Token.NULL) {
            reader.nextNull()
            return null
        }
        val dateFormat = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault())
        val dateString = reader.nextString()
        return dateFormat.parse(dateString)
    }

    @ToJson
    fun toJson(writer: JsonWriter, @Nullable date: Date?) {
        val dateFormat = SimpleDateFormat("yyyy-MM-dd", Locale.getDefault())
        if (date != null) {
            writer.value(dateFormat.format(date))
        } else {
            writer.nullValue()
        }
    }
}

val moshi = Moshi.Builder()
    .add(NullableDateAdapter())
    .build()

val jsonAdapter = moshi.adapter(YourModelClass::class.java)
val yourModel = jsonAdapter.fromJson(jsonString)