RestEasyClientBuild register ResteasyJackson2Provider - WARN about duplicate

Question

I am using the org.jboss.resteasy.client.jaxrs.ResteasyClientBuilder to build a REST client in the following way:

ResteasyClient client = (new ResteasyClientBuilder())
    .maxPooledPerRoute(5)
    .connectionPoolSize(10)
    .socketTimeout(10L, TimeUnit.SECONDS)
    .register(jacksonProvider)
    .register(new RestClientLogger())
    .register(new RestClientMDCFilter())
    .build();

The jacksonProvider that is registered there is a ResteasyJackson2Provider jacksonProvider = new ResteasyJackson2Provider(); which comes with a custom ObjectMapper that is important for deserialization. So far so good, the problem is, that I get the following warning in JBoss:

10:31:38,414 WARN  [org.jboss.resteasy.resteasy_jaxrs.i18n] (default-threads - 1) RESTEASY002155: Provider class org.jboss.resteasy.plugins.providers.jackson.ResteasyJackson2Provider is already registered.  2nd registration is being ignored.

This makes sense if I check the documentation when there already has been an instance of the same class that has been registered before. I used a decompiler to check what ResteasyClientBuilder is doing and was able to see, that it scans the classpath for jars that contain a resource that describes what "built in" providers should be registered.

One of the jboss provided implementations is now apparently already defining a ResteasyJackson2Provider that is registered there making it impossible for me to later register my own instance of it.

What are my options here? I need to get my version of the ResteasyJackson2Provider - or at least the ObjectMapperinto the client. Can I somehow replace the existing one?

Answer 1

I had the same issue, but I did not want to remove the resteasy-jackson2-provider dependencies because we added that dependency explicitly for other parts of the system (using undertow, not full AS).

Turns out you can just extend the org.jboss.resteasy.plugins.providers.jackson.ResteasyJackson2Provider without adding/overriding anything so you can register it with a higher priority than the default org.jboss.resteasy.plugins.providers.jackson.ResteasyJackson2Provider picked up from the classpath (which is registered without a priority). This way you ensure your ResteasyJackson2Provider will be chosen over the one picked up via classpath scanning.

Extending to a "custom" ResteasyJackson2Provider:

public class CustomResteasyJackson2Provider extends ResteasyJackson2Provider {
}

Plug that in to the ResteasyClientBuilder with your customized ObjectMapper:

ObjectMapper objectMapper = new ObjectMapper();
// customize your objectMapper here...
CustomResteasyJackson2Provider jacksonProvider = new CustomResteasyJackson2Provider();
jacksonProvider.setMapper(objectMapper); // add objectMapper to provider

// register provider to client
ResteasyClient client = new ResteasyClientBuilder()
     .register(jacksonProvider, 100) // any priority over 0 will do
     .build();

Hope this helps.

Answer 2

If you want to use your own packaged 'resteasy-jackson2-provider' jars, then one of the ways you can skip loading the resteasy provider provided my JBoss by excluding the below dependencies using the jboss-deployment-structure.xml,

<?xml version="1.0" encoding="UTF-8"?>
<jboss-deployment-structure>
    <deployment>
        <exclusions>
            <module name="org.jboss.resteasy.resteasy-jackson-provider"/>
            <module name="org.jboss.resteasy.resteasy-jettison-provider"/>
            <module name="org.jboss.resteasy.resteasy-jackson2-provider"/>
        </exclusions>
    </deployment>
</jboss-deployment-structure>