protected boolean isLeapYear(final 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
spring-cloud-alibaba-starters/spring-cloud-starter-alibaba-schedulerx/src/main/java/com/alibaba/cloud/scheduling/schedulerx/util/CronExpression.java