public int add(Object o) {
        HollowTypeMapper typeMapper = getTypeMapper(o.getClass(), null, null);
        return typeMapper.write(o);
    }
@Test
    public void testDate() throws IOException {
        HollowObjectMapper mapper = new HollowObjectMapper(writeStateEngine);

        long time = System.currentTimeMillis();

        mapper.add(new Date(time));

        roundTripSnapshot();

        int theOrdinal = readStateEngine.getTypeState("Date").maxOrdinal();

        GenericHollowObject obj = new GenericHollowObject(readStateEngine, "Date", theOrdinal);

        Assert.assertEquals(time, obj.getLong("value"));
    }