public boolean isNewer(Timestamped<T> other) {
        return isNewerThan(checkNotNull(other).timestamp());
    }
@Test
    public final void testIsNewer() {
        Timestamped<String> a = new Timestamped<>("a", TS_1_2);
        Timestamped<String> b = new Timestamped<>("b", TS_1_1);
        assertTrue(a.isNewer(b));
        assertFalse(b.isNewer(a));
    }