saveable-state-provider.kt

// somewhere at the top, create & remember instance of SaveableStateHolder 
val saveableStateHolder = rememberSaveableStateHolder()

// called for every destination with a unique key in navigation structure
// (when created or active)
saveableStateHolder.SaveableStateProvider(key = ...) {
  // composable content whose rememberSaveable values will be saved with 
  // the given key
}

// remove the saved state, happens during backward navigation i.e destination 
// is removed from the backstack.
saveableStateHolder.removeState(key = ...)