@Override
    public abstract int compare(@NonNull String id1, @NonNull String id2);
@Test
    public void testCompareCaseInsensitive() {
        IdStrategy idStrategy = IdStrategy.CASE_INSENSITIVE;
        assertTrue(idStrategy.compare("user1", "user2") < 0);
        assertTrue(idStrategy.compare("user2", "user1") > 0);
        assertEquals(0, idStrategy.compare("user1", "user1"));
        assertTrue(idStrategy.compare("USER1", "user2") < 0);
        assertTrue(idStrategy.compare("USER2", "user1") > 0);
        assertEquals(0, idStrategy.compare("User1", "user1"));
    }