### Question:
RedisStateMapJsonSerDe implements RedisStateMapSerDe { @Override public RedisStateMap deserialize(final byte[] data) throws IOException { if (data == null || data.length == 0) { return null; } final RedisStateMap.Builder builder = new RedisStateMap.Builder(); try (final JsonParser jsonParser = jsonFactory.createParser(data)) { final JsonNode rootNode = jsonParser.readValueAsTree(); builder.version(rootNode.get(FIELD_VERSION).asLong()); builder.encodingVersion(rootNode.get(FIELD_ENCODING).asInt()); final JsonNode stateValuesNode = rootNode.get(FIELD_STATE_VALUES); stateValuesNode.fields().forEachRemaining(e -> builder.stateValue(e.getKey(), e.getValue().asText())); } return builder.build(); }  @Override byte[] serialize(final RedisStateMap stateMap); @Override RedisStateMap deserialize(final byte[] data); static final String FIELD_VERSION; static final String FIELD_ENCODING; static final String FIELD_STATE_VALUES; }### Answer:
@Test public void testDeserializeWhenNull() throws IOException { Assert.assertNull(serDe.deserialize(null)); }