|| str_offset < 0 || str_offset + len > str.length)
|| str_offset < 0 || str_offset > str.length - len)
  public synchronized StringBuffer insert(int offset,                                          char[] str, int str_offset, int len)  {    if (offset < 0 || offset > count || len < 0        || str_offset < 0 || str_offset + len > str.length)      throw new StringIndexOutOfBoundsException();    ensureCapacity_unsynchronized(count + len);    System.arraycopy(value, offset, value, offset + len, count - offset);    System.arraycopy(str, str_offset, value, offset, len);    count += len;    return this;  }