@JsonTypeInfo property added twice to generated JSON: add support for `JsonType.As.EXISTING_PROPERTY`

Hi,

I have an abstract super class annotated with

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type")

where type is an existing property of the class.

The full class hierarchy looks like this:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY, property = "type")
@JsonSubTypes({
                      @JsonSubTypes.Type(value = SubClassA.class, name = "a"),
                      @JsonSubTypes.Type(value = SubClassB.class, name = "b")
              })
public abstract class AbstractSuperClass {
    @Transient
    private String type;

    protected AbstractSuperClass() {
        setType(getTypeValue());
    }
    protected abstract String getTypeValue();

    // getters and setters
}

public class SubClassA extends AbstractSuperClass {
    private double a;

    public SubClassA(double a) {
        this.a = a;
    }

    // getters and setters

    @Override
    protected String getTypeValue() {
        return "a";
    }
}

public class SubClassB extends AbstractSuperClass {

    private int b;

    public SubClassB(int b) {
        this.b = b;
    }

    // getters and setters

    @Override
    protected String getTypeValue() {
        return "b";
    }
}

Now when a SubClass of this class gets serialised, the type is added twice to the generated JSON. E.g. the JSON for a SubClassB would look like this:

{"type":"b","type":"b","b":42}

For the most part this does not seem to be an issue, but some clients (e.g. Postman) refuse this as Malformed JSON.

I know I could add e.g. @JsonTypeId or @JsonIgnore but in that case, type will not be included in generated JSON when using a List<AbstractSuperClass>, which is what I definitely need.

I assume that include = JsonTypeInfo.As.EXISTING_PROPERTY would solve my problem but this results in java.lang.IllegalStateException: Do not know how to construct standard type serializer for inclusion type: EXISTING_PROPERTY

[cowtowncoder]

Original fix was in 2.5.0. There is one related fix (#222) that will be included in 2.6.0 (and 2.6.0-rc3 if such is released before 2.6.0 final).

[ouaibsky]

Hi

Can you tell me in which version this fix has been released ? Thx Christophe