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…

Accepted Answer

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.

RestEasyClientBuild register ResteasyJackson2Provider - WARN about duplicate

Solution

Problem