public static TimeWindows ofSizeWithNoGrace(final Duration size) throws IllegalArgumentException {
        return ofSizeAndGrace(size, ofMillis(NO_GRACE_PERIOD));
    }
@Test
    public void windowSizeMustNotBeZero() {
        assertThrows(IllegalArgumentException.class, () -> TimeWindows.ofSizeWithNoGrace(ofMillis(0)));
    }