HowTo do sum aggregation for data inside a List<Object> [Question]

[Morons]

I seem to have a compounded error

The first Error is I do not know How to do the sum aggregation with my data classes, I guess the serialization
problem will go away once I have fixed it.

I have a Data Class(es)

data class MyClass(
	val items: List<Item>,
	val timestamp: Long = Instant.now().atOffset(ZoneOffset.UTC).toEpochSecond(),
	@BsonId
	val id: String = ObjectId().toString()
)

data class Item(
	val name: String,
	val price: Double,
	val qty: Double
)

I need to sum the price

MyClass::id = id

My Attempt

override suspend fun sumPrice(id: String): Double {
 data class Result(val sumPrice: Double)
	return collection.aggregate<MyClass>(
		match(MyClass::id eq id),
		group(Result::sumPrice sum listOf(Item::price))
	).first()?.sumPrice ?: 0.0
}

This give me some problems

java.io.UncheckedIOException

Caused by: com.fasterxml.jackson.databind.exc.InvalidDefinitionException: No serializer found for class com.mongodb.client.model.SimpleExpression and no properties discovered to create BeanSerializer (to avoid exception, disable SerializationFeature.FAIL_ON_EMPTY_BEANS) (through reference chain: com.mongodb.client.model.BsonField["value"])

Please Assist and Teach me

[Morons]

I have tried the mongo way also

val result =  collection.aggregate<MyClass>(
	"""[ { ${match()} : { _id: $ id } }, { $project: { _id: { 
		|$ sumPrice: { $sum: '$ items.price' } } } } ]""".trimMargin()
).first()?.sumPrice ?: 0.0

and yeh...

[zigzago]

Look at this unit test: https://github.com/Litote/kmongo/blob/master/kmongo-core-tests/src/main/kotlin/org/litote/kmongo/AggregateTypedTest.kt#L122 (and use gitter please ;)) https://gitter.im/kmongoo/Lobby

[Morons]

The unit test does not solve the issue, the aggrigation is simple vs my sample
I will move this question to gitter