protected void addSectionAt(int index, @NotNull TextSection section) {
    synchronized (mySections) {
      mySections.add(index, section);
      for (Iterator<TextSection> iterator = mySections.iterator(); iterator.hasNext();) {
        TextSection textSection = iterator.next();
        if (textSection == null) {
          LOG.error("index: " + index + " size: " + mySections.size());
          iterator.remove();
        }
      }
    }
  }
protected void addSectionAt(int index, @NotNull TextSection section)