Duplicate JSON property when @JsonTypeInfo.property is also regular bean property

[vojtechhabarta]

Consider following example which uses Jackson library:

@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, property = "kind", include = JsonTypeInfo.As.PROPERTY)
@JsonSubTypes({
    @JsonSubTypes.Type(value = DuplicateKind1.class, name = "kind_1"),
    @JsonSubTypes.Type(value = DuplicateKind2.class, name = "kind_2"),
})
abstract class DuplicateKind {
    public String kind;
}
class DuplicateKind1 extends DuplicateKind {
}
class DuplicateKind2 extends DuplicateKind {
}

If instance is created and serialized using Jackson:

DuplicateKind1 object = new DuplicateKind1();
object.kind = "kind_invalid";
System.out.println(new ObjectMapper().writeValueAsString(object));

Jackson generates following invalid JSON:

{
    "kind": "kind_1",
    "kind": "kind_invalid"
}

where first kind property comes from @JsonTypeInfo annotation and second comes from DuplicateKind.kind field. (Tested with Jackson 2.9.7)

Here are relevant issues tracked in jackson-databind repository: FasterXML/jackson-databind#2022, FasterXML/jackson-databind#1410.

To resolve this issus either:

• remove kind field (preferred)
• change include = JsonTypeInfo.As.PROPERTY to EXISTING_PROPERTY

Tagged unions

Typescript-generator can generate tagged unions (#81) for Jackson polymorphic classes that uses @JsonTypeInfo annotation with include = JsonTypeInfo.As.PROPERTY.

New

Typescript-generator can now detect mentioned duplicate property issue and does not generate tagged unions for such classes. In addition to this it also logs warning.

[vojtechhabarta]

Change released in v2.16.538.