### Question:
DateTimeDay extends DateTimePeriod { @Override public DateTimeDuration getDefaultSubDuration() { return DateTimeDuration.HOUR; } protected  DateTimeDay(DateTime start, DateTime end); @Override DateTimePeriod getNext(); @Override DateTimePeriod getPrevious(); @Override DateTimeDuration getDefaultSubDuration();  }### Answer:
@Test public void getDefaultSubDuration() throws Exception { DateTimePeriod period0 = DateTimePeriod.createDay(2009, 1, 1, DateTimeZone.UTC); Assert.assertEquals(DateTimeDuration.HOUR, period0.getDefaultSubDuration()); }