@Override
        public void appendTo(StringBuffer buffer, int value) {
            mRule.appendTo(buffer, value);
        }
Returns an estimate for the maximum length date that this date
formatter will produce. The actual formatted length will almost always
be less than or equal to this amount.
@return an estimate of the maximum length
xmppserver/src/main/java/org/jivesoftware/util/FastDateFormat.java