Jackson @JsonIdentityInfo with always embedded whole objects during serialization

DisableJsonIdentityInfoReferenceSerialization.java

import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationConfig;
import com.fasterxml.jackson.databind.introspect.Annotated;
import com.fasterxml.jackson.databind.introspect.JacksonAnnotationIntrospector;
import com.fasterxml.jackson.databind.introspect.ObjectIdInfo;

import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;


public class JsonIdentityInfoSerialization {

    /**************************************************************************
     ******************************* POJOS *************************************
     ***************************************************************************/

    /******************************* Contact.java ****************************/
    public static class Contact {
        @JsonProperty("id")
        private int id;

        @JsonIdentityReference(alwaysAsId = true)
        @JsonProperty("phones")
        private List<Phone> phones;

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public List<Phone> getPhones() {
            return phones;
        }

        public void setPhones(List<Phone> phones) {
            this.phones = phones;
        }
    }

    /******************************* Phone.java ****************************/
    @JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
            resolver = MyObjectIdResolver.class,
            property = "id", scope = Phone.class)
    public static class Phone {
        @JsonProperty("id")
        private int id;

        @JsonProperty("n")
        private String n;

        public Phone() {
        }

        public int getId() {
            return id;
        }

        public void setId(int id) {
            this.id = id;
        }

        public String getN() {
            return n;
        }

        public void setN(String n) {
            this.n = n;
        }
    }

    /**************************************************************************
     ******************************* OBJECT MAPPERS ****************************
     ***************************************************************************/

    public static ObjectMapper defaultObjectMapper() {
        return new ObjectMapper();
    }

    /****** this mapper ignores @JsonIdentityInfo during serialization **********/
    public static ObjectMapper ignoreJsonIdentityInfoMapper() {
        ObjectMapper m = new ObjectMapper();

        SerializationConfig config = m.getSerializationConfig()
                .with(new JacksonAnnotationIntrospector() {
                    @Override
                    public ObjectIdInfo findObjectIdInfo(final Annotated ann) {
                        return null;
                    }
                });
        m.setConfig(config);

        return m;
    }

    /** this mapper ignores @JsonIdentityReference(alwaysAsId = true) during serialization **/
    public static ObjectMapper ignoreJsonIdentityReferenceMapper() {
        ObjectMapper m = new ObjectMapper();
        SerializationConfig config2 = m.getSerializationConfig()
                .with(new JacksonAnnotationIntrospector() {
                    @Override
                    public ObjectIdInfo findObjectReferenceInfo(Annotated ann, ObjectIdInfo objectIdInfo) {
                        return null;
                    }
                });
        m.setConfig(config2);
        return m;
    }

    /**************************************************************************
     *******************************TESTS **************************************
     ***************************************************************************/

    public static void main(String[] args) throws Exception {

        // init data
        Phone p1 = new Phone();
        p1.setId(3);
        p1.setN("b");
        Phone p2 = new Phone();
        p2.setId(2);
        p2.setN("a");

        List<Phone> phones = new ArrayList<>();
        phones.add(p1);
        phones.add(p2);
        phones.add(p1); // add p1 2 times

        Contact contact = new Contact();
        contact.setPhones(phones);
        contact.setId(1);

        ArrayList<Contact> contacts = new ArrayList<>();
        contacts.add(contact); // add same contact 2 times
        contacts.add(contact);

        System.out.println("\nObjectMapper1 without customisations");
        fullTest(defaultObjectMapper(), contacts);
        System.out.println("\nObjectMapper2 with ignoreJsonIdentityInfoMapper");
        fullTest(ignoreJsonIdentityInfoMapper(), contacts);
        System.out.println("\nObjectMapper3 with ignoreJsonIdentityReferenceMapper");
        fullTest(ignoreJsonIdentityReferenceMapper(), contacts);

    }

    private static void fullTest(ObjectMapper mapper, ArrayList<Contact> testData) throws IOException {
        System.out.println("Serialization tests:");
        System.out.println("Contact      : " + mapper.writeValueAsString(testData.get(0)));
        System.out.println("List<Contact>: " + mapper.writeValueAsString(testData));
        System.out.println("Deserialization tests:");
        deserializationTest(mapper, "{\"id\":1,\"phones\":[{\"id\":3,\"n\":\"a\"},{\"id\":2,\"n\":null},3]}");
        deserializationTest(mapper, "{\"id\":1,\"phones\":[{\"id\":3,\"n\":\"b\"},{\"id\":2,\"n\":null},{\"id\":3,\"n\":\"b\"}]}");
        deserializationTest(mapper, "{\"id\":1,\"phones\":[1,2,1]}");
    }

    private static void deserializationTest(ObjectMapper mapper, String json) throws IOException {

        System.out.println("From: " + json);
        Contact result = mapper.readValue(json, Contact.class);
        System.out.println("To  : " + mapper.writeValueAsString(result));

    }

    /**************************************************************************
     **************** ObjectIdResolver used for deserialization ****************
     ***************************************************************************/

    private static class MyObjectIdResolver implements ObjectIdResolver {
        private Map<ObjectIdGenerator.IdKey, Object> _items = new HashMap<>();

        @Override
        public void bindItem(ObjectIdGenerator.IdKey id, Object pojo) {
            if (!_items.containsKey(id)) _items.put(id, pojo);
        }

        @Override
        public Object resolveId(ObjectIdGenerator.IdKey id) {
            Object object = _items.get(id);
            if (object != null) return object;

            try {
                object = id.scope.getConstructor().newInstance(); // create instance
                id.scope.getMethod("setId", int.class).invoke(object, id.key);  // set id
            } catch (Exception e) {
                e.printStackTrace();
            }

            return object;
        }

        @Override
        public ObjectIdResolver newForDeserialization(Object context) {
            return new MyObjectIdResolver();
        }

        @Override
        public boolean canUseFor(ObjectIdResolver resolverType) {
            return resolverType.getClass() == getClass();
        }
    }

OUTPUT:

ObjectMapper1 without customisations
Serialization tests:
Contact : {"id":1,"phones":[3,2,3]}
List: [{"id":1,"phones":[3,2,3]},{"id":1,"phones":[3,2,3]}]
Deserialization tests:
From: {"id":1,"phones":[{"id":3,"n":"a"},{"id":2,"n":null},3]}
To : {"id":1,"phones":[3,2,3]}
From: {"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":null},{"id":3,"n":"b"}]}
To : {"id":1,"phones":[3,2,3]}
From: {"id":1,"phones":[1,2,1]}
To : {"id":1,"phones":[1,2,1]}

ObjectMapper2 with ignoreJsonIdentityInfoMapper
Serialization tests:
Contact : {"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":"a"},{"id":3,"n":"b"}]}
List: [{"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":"a"},{"id":3,"n":"b"}]},{"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":"a"},{"id":3,"n":"b"}]}]
Deserialization tests:
From: {"id":1,"phones":[{"id":3,"n":"a"},{"id":2,"n":null},3]}
To : {"id":1,"phones":[{"id":3,"n":"a"},{"id":2,"n":null},{"id":3,"n":"a"}]}
From: {"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":null},{"id":3,"n":"b"}]}
To : {"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":null},{"id":3,"n":"b"}]}
From: {"id":1,"phones":[1,2,1]}
To : {"id":1,"phones":[{"id":1,"n":null},{"id":2,"n":null},{"id":1,"n":null}]}

ObjectMapper3 with ignoreJsonIdentityReferenceMapper
Serialization tests:
Contact : {"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":"a"},{"id":3,"n":"b"}]}
List: [{"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":"a"},{"id":3,"n":"b"}]},{"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":"a"},{"id":3,"n":"b"}]}]
Deserialization tests:
From: {"id":1,"phones":[{"id":3,"n":"a"},{"id":2,"n":null},3]}
To : {"id":1,"phones":[{"id":3,"n":"a"},{"id":2,"n":null},{"id":3,"n":"a"}]}
From: {"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":null},{"id":3,"n":"b"}]}
To : {"id":1,"phones":[{"id":3,"n":"b"},{"id":2,"n":null},{"id":3,"n":"b"}]}
From: {"id":1,"phones":[1,2,1]}
To : {"id":1,"phones":[{"id":1,"n":null},{"id":2,"n":null},{"id":1,"n":null}]}