@RequiresWriteLock
  public void appendChange(int index, @NotNull List<? extends CharSequence> newContent) {
    LOG.assertTrue(isInsideCommand());
    int outputStartLine = getLineStart(index);
    int outputEndLine = getLineEnd(index);

    DiffUtil.applyModification(myDocument, outputEndLine, outputEndLine, newContent);

    int newOutputEndLine = outputEndLine + newContent.size();
    moveChangesAfterInsertion(index, outputStartLine, newOutputEndLine);
  }
@RequiresWriteLock
  public void appendChange(int index, @NotNull List<? extends CharSequence> newContent)