I've just tried https://github.com/apache/cxf/pull/214. The client proxy does not declare getProperty()/setProperty() methods even if ExtensionManagerBus is used as a bean class, but since Weld is using subclassing, the methods are still accesible - declared on the subclass of the proxy - ExtensionManagerBus. In case of Bus bean class the client proxy subclass is java.lang.Object, i.e. no getProperty()/setProperty() methods are accessible.