SavedStateHandle.java

public final class SavedStateHandle {
  final Map<String, Object> mRegular;
  ...
  private final SavedStateProvider mSavedStateProvider = new SavedStateProvider() {
    @NonNull
    public Bundle saveState() {
      Set<String> keySet = mRegular.keySet();
      ArrayList keys = new ArrayList(keySet.size());
      ArrayList value = new ArrayList(keys.size());
      ...
      Bundle res = new Bundle();
      res.putParcelableArrayList("keys", keys);
      res.putParcelableArrayList("values", value);
      return res;
    }
  };
  ...
}