@Nullable
  public Int2IntMap getOldToNewLineMapping() {
    if (myOldToNewLines == null) {
      myOldToNewLines = doGetLineMapping(true);
      if (myOldToNewLines == null) return null;
    }
    return myOldToNewLines.get();
  }
@Nullable
  public Int2IntMap getOldToNewLineMapping()