public static Builder custom() {
        return new Builder();
    }
@Test(expected = IllegalStateException.class)
    public void shouldNotUseWitIntervalFunctionInOpenStateAndWaitDurationInOpenStateTogether() {
        custom()
            .waitDurationInOpenState(Duration.ofMillis(3333))
            .waitIntervalFunctionInOpenState(IntervalFunction.of(Duration.ofMillis(1234)))
            .build();
    }