protected boolean isLeapYear(int year) {
        return ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0));
    }
NOT YET IMPLEMENTED: Returns the final time that the 
<code>CronExpression</code> will match.
server/core/src/main/java/com/ke/schedule/server/core/common/CronExpression.java