private static void visitMillisecondToken(int repetitions, JQueryDateTimePatternBuilder builder) {
        // actually also accepts no leading zeros
        builder.appendMillisecondsWithLeadingZeros();
    }
Millisecond token 'S'. Always interpreted as optional leading zeros.
primefaces/src/main/java/org/primefaces/convert/CombinedDateTimePatternTokenVisitor.java