Apache CXF's wsdl2java support is pluggable. There is a META-INF/tools-plugin.xml descriptor that allows you to define custom generators ("frontend profiles"). Sample shows howto implement and use Service Endpoint Interface (SEI) generator. Custom generator extends the default one, but provides a different velocity template. This velocity template is identical to the default one, except that sample javadoc added for generated SEI.
Inspired by https://github.com/playframework/play-soap#wsdl2java