docs: public final void insertNullElementsAt(int index, int count)
    {
      if (tc.isEntryEnabled())
        SibTr.entry(
          tc,
          "insertNullElementsAt",
          new Object[] { new Integer(index), new Integer(count)});
  
      for (int i = index; i < index + count; i++)
        add(i, null);
  
      if (tc.isEntryEnabled())
        SibTr.exit(tc, "insertNullElementsAt");
    }