Change:

     * @throws IndexOutOfBoundsException
     * If <tt>off</tt> is negative, or <tt>len</tt> is negative,
     * or <tt>off+len</tt> is negative or greater than the length
     * of the given string

to a more standard, less awkward and fully equivalent:

     * @throws IndexOutOfBoundsException
     * If <tt>off</tt> is negative, or <tt>len</tt> is negative,
     * or <tt>len</tt> greater than <tt>str.length() - off</tt>