System.arraycopy(value, end, value, end + delta, count - end);
VMSystem.arraycopy(value, end, value, end + delta, count - end);
  public synchronized StringBuffer replace(int start, int end, String str)  {    if (start < 0 || start > count || start > end)      throw new StringIndexOutOfBoundsException(start);    int len = str.count;    // Calculate the difference in 'count' after the replace.    int delta = len - (end > count ? count : end) + start;    ensureCapacity_unsynchronized(count + delta);    if (delta != 0 && end < count)      System.arraycopy(value, end, value, end + delta, count - end);    str.getChars(0, len, value, start);    count += delta;    return this;  }