public static CumulativeWindowAssigner of(Duration maxSize, Duration step) {
        return new CumulativeWindowAssigner(maxSize.toMillis(), step.toMillis(), 0, true);
    }
@Test
    public void testInvalidParameters1() {
        assertThatThrownBy(
                        () ->
                                CumulativeWindowAssigner.of(
                                        Duration.ofSeconds(-2), Duration.ofSeconds(1)))
                .isInstanceOf(IllegalArgumentException.class)
                .hasMessageContaining("step > 0 and size > 0");
    }