WIldfly | Jackson polymorphism not considered

Question

I am developing a REST service within Wildfly 23.0.2.Final. I have an EAR which contains an EJB and a WAR module. The WAR module is the JAX-RS service. Most of my entities leverage polymorphism, such as:

public class EchoResponse extends AjaxBody<Boolean> {

    private static final long serialVersionUID = 4762378876367068194L;

    /**
     * 
     */
    public EchoResponse() {
        super();
    }

    /**
     * @param result
     */
    public EchoResponse(Boolean result) {
        super(result);
    }

}

which extends

@JsonTypeInfo(
          use = JsonTypeInfo.Id.NAME, 
          include = JsonTypeInfo.As.PROPERTY, 
          property = "__type")
@JsonSubTypes({ 
      @Type(value = EchoResponse.class, name = "EchoResponse"),
      ...
})
public class AjaxBody<T> implements Serializable {
    
    private static final long serialVersionUID = 3528022080494570805L;
    
    private T result;
    
    public T getResult() {
        return result;
    }
    
    public void setResult(T result) {
        this.result = result;
    }

    public AjaxBody() {
    }
    
    public AjaxBody(T result) {
        this.setResult(result);
    }

}

However, polymorphism is not considered at all and in the responses I do not receive the __type attribute, causing the client module (a Java web application built over Spring and deployed in a simple Tomcat instance) to error out while trying to unmarshall the response (both the service and the client share the same Java module where entities are defined).

I also noticed that all annotations are ignored, for example @JsonIgnore.

I already checked my Jackson dependencies, and confirmed they are all in provided scope. Also, I tried adding the jboss-deployment-structure.xml as follows:

<jboss-deployment-structure xmlns="urn:jboss:deployment-structure:1.2">
    <ear-subdeployments-isolated>true</ear-subdeployments-isolated>

    <sub-deployment name="scoofer-web.war">
        <exclusions>
            <module name="org.jboss.resteasy.resteasy-jackson-provider" />
        </exclusions>
        <dependencies>
            <module name="org.jboss.resteasy.resteasy-jackson2-provider" services="import" />
        </dependencies>
    </sub-deployment>
</jboss-deployment-structure>

One more note: all the endpoints support both application/json and application/xml: if invoked via XML, the attribute __type is present in the body node, as expected.

What am I still missing?

Answer 1

I've filed RESTEASY-2948 as this is not documented properly. To fix this you need to set the resteasy-prefer-jackson-over-jsonb property. The simplest way is to use CLI to change the value in the subsystem:

/subsystem=jaxrs:write-attribute(name=resteasy-prefer-jackson-over-jsonb, value=true)

This should also not require you to include a jboss-deployment-structure.xml. One thing to note though is this does affect all deployments.