Creating custom CartItem, from which extend

[crevillo]

Hi there. I'm reading the docs and following for my project. For creating my custom CartItem entity doc suggest to extend from
use Sylius\Component\Cart\Model\CartItem as BaseCartItem;

After that, in the ItemResolver it calls a setVariant function

$item->setVariant($product);

but there's no setVariant in the CartItem i'm extending.

What i see is i have that function defined at https://github.com/Sylius/Core/blob/master/Model/OrderItem.php#L75, in a model extending the same CartItem i'm trying to extend.

so, to use this setVariant, shouldn't we extend from Sylius\Core\Model\OrderItem? or am i understanding it totally wrong?

Thanks