protected boolean isLeapYear(int year) {
        return ((year % 4 == 0 && year % 100 != 0) || (year % 400 == 0));
    }
Advance the calendar to the particular hour paying particular attention
to daylight saving problems.

@param cal the calendar to operate on
@param hour the hour to set
lts-core/src/main/java/com/github/ltsopensource/core/support/CronExpression.java