How to serialize single-valued @Data object using Jackson without nesting (e.g. {"id":123}, not {"id":{"value":123}})?

I created an interface which has getValue() which annotated as @JsonValue:

public interface LongValue {    @JsonValue    long getValue();}

Then implemented it in every @Data classes. note that actual implementation of getValue() will be automatically generated by Lombok:

@Datapublic final class SomeId implements LongValue, Serializable {    private final long value;}

With that I've got the test SomeDTOTest passed - SomeDTO is serialized to {"id":123} as I expected.

You can write custom Serializer for this class.

E.g.:

class CustomSerializer extends StdSerializer<SomeId>{    protected CustomSerializer(Class<SomeId> t) {        super(t);    }    @Override    public void serialize(SomeId someId, JsonGenerator gen, SerializerProvider serializers)            throws IOException, JsonProcessingException {        gen.writeNumber(someId.getValue());     }   }

Now use this serializer to serialize SomeId class:

 ObjectMapper mapper = new ObjectMapper(); SimpleModule module = new SimpleModule(); module.addSerializer(new CustomSerializer(SomeId.class));        mapper.registerModule(module); SomeDTO dto = new SomeDTO(); dto.id = new SomeId(123);      String serialized = mapper.writeValueAsString(dto); System.out.println(serialized);             // output : {"id":123}