@Override
    public int size() {
        if (entries == null) {
            return 0;
        }
        return entries.size();
    }
@Test
    public void testSize_whenNotEmpty() {
        List<Map.Entry> entries = new ArrayList<>();
        entries.add(new MapEntrySimple(null, null));
        ResultSet resultSet = new ResultSet(entries, IterationType.KEY);
        assertEquals(1, resultSet.size());
    }