NavGraph.kt

// NavGraph.kt
interface NavGraph {
    val navGraph: NavGraphBuilder.(NavEventController) -> Unit
}

// ShoppingNavGraph.kt
internal class ShoppingNavGraph : NavGraph {
    override val navGraph: NavGraphBuilder.(NavEventController) -> Unit = { navEventController ->
        composable<ShoppingDestination.Details> {
            val route: ShoppingDestination.Details = navEntry.toRoute()
            ShoppingDetails(
                itemId = route.itemId,
                onCheckoutClick = {
                    navEventController.sendEvent(ShoppingEvent.OnCheckoutClick)
                },
                onMyCoupounsClick = {
                    navEventController.sendEvent(ShoppingEvent.OnMyCoupounsClick)
                }
            )
        }

         composable<ShoppingDestination.Cart> {
           // [...] all the other declarations
    }
}