@Test
 public void testTransitive_apiStringApi() {
   assertEquals(
       apiDateTime1, DateTimes.toDateTime(DateTimes.toString(apiDateTime1), TIME_ZONE_ID1));
   assertEquals(
       apiDateTime2, DateTimes.toDateTime(DateTimes.toString(apiDateTime2), TIME_ZONE_ID2));
   assertEquals(
       apiDateTime3, DateTimes.toDateTime(DateTimes.toString(apiDateTime3), TIME_ZONE_ID3));
 }
 @Test
 public void testToString_fromApiDateTime() {
   Assert.assertEquals(stringDateTime1, DateTimes.toString(apiDateTime1));
   Assert.assertEquals(stringDateTime2, DateTimes.toString(apiDateTime2));
   Assert.assertEquals(stringDateTime3, DateTimes.toString(apiDateTime3));
 }
 @Test
 public void testToString_fromApiDate() {
   Assert.assertEquals(stringDate1, DateTimes.toString(apiDateTime1.getDate()));
   Assert.assertEquals(stringDate2, DateTimes.toString(apiDateTime2.getDate()));
   Assert.assertEquals(stringDate3, DateTimes.toString(apiDateTime3.getDate()));
 }