code: public static Calendar trimToMidnight(Calendar calendar) {
          calendar.set(Calendar.HOUR_OF_DAY, 0);
          calendar.set(Calendar.MINUTE, 0);
          calendar.set(Calendar.SECOND, 0);
          calendar.set(Calendar.MILLISECOND, 0);
          return calendar;
      }
docs: Trims off all time information, effectively setting it to midnight
  Makes it easier to compare at just the day level
  
  @param calendar The Calendar object to trim
  @return The trimmed Calendar object