code: public static <T extends Calendar> T round(final T calendar, final int field) {
          N.checkArgNotNull(calendar, "calendar");
  
          final Calendar rounded = (Calendar) calendar.clone();
          modify(rounded, field, ModifyType.ROUND);
  
          if (rounded.getClass().equals(calendar.getClass())) {
              return (T) rounded;
          }
  
          return createCalendar(calendar, rounded.getTimeInMillis());
      }
docs: Copied from Apache Commons Lang under Apache License v2.
  <br />
  
  <p>Rounds a date, leaving the field specified as the most
  significant field.</p>
  
  <p>For example, if you had the date-time of 28 Mar 2002
  13:45:01.231, if this was passed with HOUR, it would return
  28 Mar 2002 14:00:00.000. If this was passed with MONTH, it
  would return 1 April 2002 0:00:00.000.</p>
  
  <p>For a date in a timezone that handles the change to daylight
  saving time, rounding to Calendar.HOUR_OF_DAY will behave as follows.
  Suppose daylight saving time begins at 02:00 on March 30. Rounding a
  date that crosses this time would produce the following values:
  </p>
  <ul>
  <li>March 30, 2003 01:10 rounds to March 30, 2003 01:00</li>
  <li>March 30, 2003 01:40 rounds to March 30, 2003 03:00</li>
  <li>March 30, 2003 02:10 rounds to March 30, 2003 03:00</li>
  <li>March 30, 2003 02:40 rounds to March 30, 2003 04:00</li>
  </ul>
  
  @param calendar  the date to work with, not null
  @param field  the field from {@code Calendar} or <code>SEMI_MONTH</code>
  @return the different rounded date, not null
  @throws IllegalArgumentException if the date is <code>null</code>
  @throws ArithmeticException if the year is over 280 million