public ZonedDateTime getDateTime() {
        return dateTime;
    }
@Test
    void getDateTime() {
        DateTimeStamp dateTimeStamp = new DateTimeStamp(.586);
        assertNull(dateTimeStamp.getDateTime());

        dateTimeStamp = new DateTimeStamp("2018-04-04T09:10:00.586-0100");
        assertEquals(ZonedDateTime.from(formatter.parse("2018-04-04T09:10:00.586-0100")), dateTimeStamp.getDateTime());

        dateTimeStamp = new DateTimeStamp("2018-04-04T09:10:00.586-0100", 0.18);
        assertEquals(ZonedDateTime.from(formatter.parse("2018-04-04T09:10:00.586-0100")), dateTimeStamp.getDateTime());
    }