@Nullable
  FoldRegion getRegionAt(int startOffset, int endOffset) {
    FoldRegionImpl[] found = {null};
    myMarkerTree.processOverlappingWith(startOffset, endOffset, region -> {
      if (region.getStartOffset() == startOffset && region.getEndOffset() == endOffset) {
        found[0] = region;
        return false;
      }
      return true;
    });
    return found[0];
  }
@Nullable
  FoldRegion getRegionAt(int startOffset, int endOffset)