public static Sessions withGapDuration(Duration gapDuration) {
    return new Sessions(gapDuration);
  }
@Test
  public void testDisplayData() {
    Duration gapDuration = Duration.standardMinutes(234);
    Sessions session = Sessions.withGapDuration(gapDuration);
    assertThat(DisplayData.from(session), hasDisplayItem("gapDuration", gapDuration));
  }