serializer serializer

Program.java

package com.ariel;

import com.ariel.core.Application;
import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.UUID;


/**
 * @author apineiro
 */
public class Program {
    public static void main(String[] args) throws IOException {

        Application application = new Application();
        Scanner scanner = new Scanner(System.in);

        ObjectMapper mapper = new ObjectMapper();
        mapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
        mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

        Node root = new Folder();
        root.name = "root";

        Folder music = new Folder();
        music.name = "music";
        music.parent = root;

        Folder rock = new Folder();
        rock.name = "rock";
        rock.parent = music;
        music.add(rock);

        File audio1 = new File();
        audio1.name = "Back in black.mp4";
        audio1.parent = rock;
        rock.add(audio1);

        Folder documents = new Folder();
        documents.name = "documents";
        documents.parent = root;

        File resume = new File();
        resume.name = "CV - John.pdf";
        resume.parent = documents;
        documents.add(resume);

        root.add(music);
        root.add(documents);
        root.show();

        mapper.writeValue(new java.io.File("root.json"), root);
    }
}

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type")
@JsonSubTypes({
        @JsonSubTypes.Type(value = File.class, name = "file"),
        @JsonSubTypes.Type(value = Folder.class, name = "folder")
})
@JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
        property = "id")
abstract class Node {

    public Node parent;
    public String name;
    public String id = UUID.randomUUID().toString();

    public abstract void show();

    public abstract void add(Node node);
}

class File extends Node {

    @Override
    public void show() {
        System.out.println(name);
    }

    @Override
    public void add(Node node) {

    }
}

class Folder extends Node {
    public ArrayList<Node> nodes = new ArrayList<>();

    @Override
    public void show() {
        System.out.println(name);
        for (Node node : this.nodes) {
            node.show();
        }
    }

    @Override
    public void add(Node node) {
        this.nodes.add(node);
    }
}