public static class MyIntegerSerializer
        extends JsonSerializer<Integer>
    {
        @Override
        public void serialize(Integer value, JsonGenerator gen, SerializerProvider serializers)
                throws IOException, JsonProcessingException
        {
            gen.writeNumber(String.valueOf(value));
        }
    }

    public static class MyIntegerDeserializer
            extends JsonDeserializer<Integer>
    {
        @Override
        public Integer deserialize(JsonParser p, DeserializationContext ctxt)
                throws IOException, JsonProcessingException
        {
            return p.getNumberValue().intValue();
        }
    }

    public static void main(String[] args)
            throws IOException
    {
        ObjectMapper objectMapper = new ObjectMapper(new MessagePackFactory());
        objectMapper.registerModule(
                new SimpleModule()
                        .addSerializer(Integer.class, new MyIntegerSerializer())
                        .addDeserializer(Integer.class, new MyIntegerDeserializer())
        );
        ByteArrayOutputStream out = new ByteArrayOutputStream();
        objectMapper.writeValue(out, 42);

        Integer integer = objectMapper.readValue(out.toByteArray(), Integer.class);
        System.out.println(integer);
    }

>>>> com.fasterxml.jackson.databind.JsonMappingException: writeNumber(String encodedValue) isn't supported yet