public List<Duration> calculatePreciseDuration(final Date then)
   {
      return calculatePreciseDuration(then != null ? then.toInstant() : null);
   }
@Test
   public void testCalculatePreciseDuration()
   {
      PrettyTime prettyTime = new PrettyTime();
      prettyTime.clearUnits();
      Minute minutes = new Minute();
      prettyTime.registerUnit(minutes, new ResourcesTimeFormat(minutes));
      Assert.assertEquals("41 minutes ago",
               prettyTime.format(prettyTime.calculatePreciseDuration(now.minusMinutes(40).minusSeconds(40))));
   }