public static boolean includes(final ConvertedMap data, final FieldReference field) {
        final Object target = findParent(data, field);
        final String key = field.getKey();
        return target instanceof ConvertedMap && ((ConvertedMap) target).containsKey(key) ||
            target instanceof ConvertedList && foundInList(key, (ConvertedList) target);
    }
@Test
    public void testNilInclude() throws Exception {
        final ConvertedMap data = new ConvertedMap(1);
        data.put("nilfield", null);
        assertTrue(includes(data, "nilfield"));
    }