private static synchronized String getDefaultPattern() {
        if (cDefaultPattern == null) {
            cDefaultPattern = new SimpleDateFormat().toPattern();
        }
        return cDefaultPattern;
    }
@param dateStyle date style: FULL, LONG, MEDIUM, or SHORT
@param timeStyle time style: FULL, LONG, MEDIUM, or SHORT
@param timeZone optional time zone, overrides time zone of formatted
date
@param locale optional locale, overrides system locale
@return the fast date format
xmppserver/src/main/java/org/jivesoftware/util/FastDateFormat.java