Jackson Databind NPE show case

JacksonTest.java

import com.fasterxml.jackson.annotation.*;
import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.ObjectMapper;
import org.hamcrest.core.IsEqual;
import org.junit.Assert;
import org.junit.Test;

import java.io.IOException;

public class JacksonTest {

    @JsonIgnoreProperties(ignoreUnknown = true)
    @JsonTypeInfo(use = JsonTypeInfo.Id.CLASS, include = JsonTypeInfo.As.PROPERTY, property = "_class")
    @JsonSubTypes({
            @JsonSubTypes.Type(Cat.class),
            @JsonSubTypes.Type(Dog.class)
    })
    public static abstract class Animal {
        public final static String ID = "id";

        private String id;
        public Animal() {
        }

        @JsonCreator
        public Animal(@JsonProperty(ID) String id) {
            this.id = id;
        }

        @JsonProperty(ID)
        public String getId() {
            return id;
        }
    }

    @JsonIgnoreProperties(ignoreUnknown = true)
    public static class Cat extends Animal {
        public Cat() {
            super();
        }

        @JsonCreator
        public Cat(@JsonProperty(ID) String id) {
            super(id);
        }

    }

    @JsonIgnoreProperties(ignoreUnknown = true)
    public static class Dog extends Animal {
        public Dog() {
            super();
        }

        @JsonCreator
        public Dog(@JsonProperty(ID) String id) {
            super(id);
        }
    }

    @JsonIgnoreProperties(ignoreUnknown = true)
    public static class AnimalWrapper {
        public static final String ANIMAL = "animal";
        private Animal animal;

        @JsonCreator
        public AnimalWrapper(@JsonProperty(ANIMAL) Animal animal) {
            this.animal = animal;
        }

        @JsonProperty(ANIMAL)
        public Animal getAnimal() {
            return animal;
        }
    }
    @Test
    public void shouldRun() throws IOException {
        ObjectMapper mapper = new ObjectMapper();
        JsonFactory factory = mapper.getJsonFactory();

        String id = "nice dogy";
        String serializedDog = mapper.writeValueAsString(new AnimalWrapper(new Dog(id)));
        JsonParser parser = factory.createJsonParser(serializedDog);
        AnimalWrapper wrapper = parser.readValueAs(AnimalWrapper.class);
        Assert.assertThat(wrapper.getAnimal().getId(), IsEqual.equalTo(id));
    }
}