private void shiftMapping(int shiftOffset) {
    if (myLineToOffsetMapping != null) {
      Map<Integer, Integer> newMap = new HashMap<>();
      for (Map.Entry<Integer, Integer> entry : myLineToOffsetMapping.entrySet()) {
        int newValue = entry.getValue();
        if (newValue >= 0) {
          newValue += shiftOffset;
        }
        if (newValue >= 0) {
          newMap.put(entry.getKey(), newValue);
        }
      }
      myLineToOffsetMapping = newMap;
    }
  }
private void shiftMapping(int shiftOffset)