Serialization with Polymorphisme and `EXTERNAL_PROPERTY` = duplicate property

[Adrien-dev25]

With this kind of POJO :

    public class Cage
    {
        public String id;
        public String type;

        @JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "type",
                include = JsonTypeInfo.As.EXTERNAL_PROPERTY)
        @JsonSubTypes({
                @JsonSubTypes.Type(value = Cat.class, name = "CAT"),
                @JsonSubTypes.Type(value = Dog.class, name = "DOG")
        })
        public Animal animal;
    }

    public abstract class Animal { }

    public class Cat extends Animal {
        public String firstName = "My name is cat";
    }

    public class Dog extends Animal {
        public String lastName = "My name is dog";
    }

When I serialize this :

Cage cage = new Cage();
cage.id = "123";
cage.type = "CAT";
cage.animal = new Cat();
String xml1 = MAPPER.writeValueAsString(cage);
System.out.println(xml1);

I get the following result (the property type is duplicated) :

<Cage>
  <animal>
    <firstName>My name is cat</firstName>
  </animal>
  <type>CAT</type>
  <id>123</id>
  <type>CAT</type>
</Cage>

Wouldn't be the expected result ?

<Cage>
  <animal>
    <firstName>My name is cat</firstName>
  </animal>
  <id>123</id>
  <type>CAT</type>
</Cage>

[Adrien-dev25]

Moreover when I try to deserialise the above XML to reconstitute the initial Java Cage Object with a simple

MAPPER.readerFor(Cage.class).readValue(xml1);

I get the error

tools.jackson.databind.exc.MismatchedInputException: Missing property 'animal' for external type id 'type'
 at [Source: (String)"<Cage><animal><firstName>My name is cat</firstName></animal><type>CAT</type><id>123</id><type>CAT</type></Cage>"; line: 1, column: 105] (through reference chain: tools.jackson.dataformat.xml.ser.PolymorphicExternalTest$Cage["animal"])

When I try with the same Cage Object but with JSON ObjectMapper, the serialized JSON looks like this

{
  "id":"123",
  "type":"CAT",
  "animal":{
    "firstName":"My name is cat"
  }
}

and it can be deserialized without any error.

[Adrien-dev25]

Hi @cowtowncoder
Thanks a lot for this quick fix !

[cowtowncoder]

@Adrien-dev25 you are welcome!