int snapshottableSize(long epoch) {
        if (epoch == LATEST_EPOCH) {
            return baseSize();
        } else {
            Iterator<Snapshot> iterator = snapshotRegistry.iterator(epoch);
            while (iterator.hasNext()) {
                Snapshot snapshot = iterator.next();
                HashTier<T> tier = snapshot.getDelta(SnapshottableHashTable.this);
                if (tier != null) {
                    return tier.size;
                }
            }
            return baseSize();
        }
    }
@Test
    public void testEmptyTable() {
        SnapshotRegistry registry = new SnapshotRegistry(new LogContext());
        SnapshottableHashTable<TestElement> table =
            new SnapshottableHashTable<>(registry, 1);
        assertEquals(0, table.snapshottableSize(Long.MAX_VALUE));
    }