code: public static long nextMidnightPlus(long now, long plus) {
  		long next = (now + timeZoneOffset) / DAY * DAY - timeZoneOffset;
  		next += plus;
  		if (next < now) {
  			next += DAY;
  		}
  		return next;
  	}
docs: Get next time (Unix time in milliseconds) in a day<p>
  E.g. xqbase.com will backup data every 4:00am, so the next backup will happen at:<p>
  <code>nextMidnightPlus(now, 4 * HOUR)</code>
  
  @param now current time (Unix time in milliseconds)
  @param plus milliseconds after midnight (12:00am)