Overriding customJaxrsRestEntityProviders does not work

http://www.onehippo.org/library/concepts/rest/restful-jax-rs-component-support-in-hst-2.html

On this page is described (look for "How to configure JAX-RS Extension Providers") how to add your own exception mappers. By configuring this bean in your project you are supposed to override the bean as configured in the file at classpath:/org/hippoecm/hst/site/optional/jaxrs/SpringComponentManager-rest-jackson.xml

Although I have done that, my bean is not used, so the overriding mechanism does not work.