serializable
fun <T : JvmSerializable> NonNullSavedStateHandleKey.Companion.serializable(key: String, defaultValue: T): NonNullSavedStateHandleKey<T>
fun <T : JvmSerializable> NullableSavedStateHandleKey.Companion.serializable(key: String, defaultValue: T? = null): NullableSavedStateHandleKey<T>