/** The key of the message: The check digit for ${value} is invalid, Luhn Modulo 10 checksum failed. */
    public static final String CONSTRAINTS_LuhnCheck_MESSAGE = "{constraints.LuhnCheck.message}";

    /** The key of the message: The check digit for ${value} is invalid, Modulo 10 checksum failed. */

are in <a href="#Rune_literals">rune literals</a> (except that <code>\'</code> is illegal and
<code>\"</code> is legal), with the same restrictions.
The three-digit octal (<code>\</code><i>nnn</i>)
and two-digit hexadecimal (<code>\x</code><i>nn</i>) escapes represent individual
<i>bytes</i> of the resulting string; all other escapes represent
the (possibly multi-byte) UTF-8 encoding of individual <i>characters</i>.