kmongo connot save kotlinx-datetime objects

Question

I am trying to use kmongo with kotlinx-datetime. The data class looks like this:

@Serializable
data class CustomerCount(
    @Contextual val _id: Id<CustomerCount>?,
    val counter: Int,
    @Contextual val date: LocalDateTime
) {
    constructor(counter: Int): this(
        null,
        counter,
        Clock.System.now().toLocalDateTime(TimeZone.of("Europe/Zurich"))
    )
}

When I now try to save an instance of CustomerCount to MongoDB I get the following error:

com.mongodb.MongoWriteException: Write operation error on server localhost:27017. Write error: WriteError{code=2, message=''date' must be present and contain a valid BSON UTC datetime value', details={}}.

How can I save kotlinx-datetime objects to MongoDB?