@Test
public void testIsEmpty() throws Exception {

    SafeCalendar notEmtyDate = new SafeCalendar(2016, 5, 15);
    assertThat(notEmtyDate.isEmpty()).isFalse();
    SafeCalendar emptyCalendar = SafeCalendar.EMPTY;
    assertThat(emptyCalendar.isEmpty()).isTrue();
    SafeCalendar startOfEpoch = new SafeCalendar(1970, 0, 0);
    assertThat(startOfEpoch.isEmpty()).isFalse();
}