@Nullable
  private FoldRegion getFoldRegion(@NotNull ThreeSide side, int line) {
    EditorEx editor = myViewer.getEditor(side);
    DocumentEx document = editor.getDocument();
    for (FoldRegion region : editor.getFoldingModel().getAllFoldRegions()) {
      if (region.isExpanded()) continue;
      int line1 = document.getLineNumber(region.getStartOffset());
      int line2 = document.getLineNumber(region.getEndOffset());
      if (line1 <= line && line <= line2) return region;
    }
    return null;
  }
@Nullable
  private FoldRegion getFoldRegion(@NotNull ThreeSide side, int line)