@Test
public void shouldSubtractNegativeOffset() {

  String offset = "-P1M3DT1H7M5S";
  ZonedDateTime time = ZonedDateTime.parse("2017-02-25T09:14:16.22Z");
  ZonedDateTime offsetTime = subtractOffset(time, offset);
  assertThat(offsetTime, is(ZonedDateTime.parse("2017-03-28T10:21:21.22Z")));
}