@Override
  public @Nullable GutterIconRenderer calcGutterIconRenderer(@NotNull CustomFoldRegion region) {
    assert myItem.getFoldRegion() == region || myItem.getFoldRegion() == null;
    return myItem.calcFoldingGutterIconRenderer();
  }
@Override
  public @Nullable GutterIconRenderer calcGutterIconRenderer(@NotNull CustomFoldRegion region)