How to handle relations one-to-many in SwiftData without getting `unknown related type`

Question

I am struggling with probably simple issue but at the moment I cannot see why it appears. So in SwiftData I want to create an object and later I wish to build related object and assign it. Lets lets jump into code, models look like following:

@Model
class Person {
     var name: String
     var age: Int
     var cars: [CarModel]?
}

@Model
class CarModel {
     var name: String
     var owner: Person?
}

With such construction I create Car first, then I want to assign a person to it. Person object is newly created, not yet stored in DB. When assigning Person to Car I get the following error Unknown related type:

var car = CarModel()
var owner = Person()
car.owner = owner

Do you have any clues? Any help appreciated :)