ViewModelStore
Class to store ViewModels.
An instance of ViewModelStore must be retained through configuration changes: if an owner of this ViewModelStore is destroyed and recreated due to configuration changes, new instance of an owner should still have the same old instance of ViewModelStore.
If an owner of this ViewModelStore is destroyed and is not going to be recreated, then it should call clear on this ViewModelStore, so ViewModels would be notified that they are no longer used.
Use ViewModelStoreOwner.viewModelStore to retrieve a ViewModelStore for activities and fragments.