Set init-param in code or with servlet annotation

Vaadin 7 book (4.83) states:-

The descriptor is not needed with Servlet API 3.0, where you can define servlets also as web fragments, with the @WebServlet annotation, or programmatically.

I have tried things like-
@WebServlet (initParams={ @WebInitParam(name=“UI”, value=“vaadinservlet2.Greeter”)})

But it does not work for me!

Example code for using annotations and programmatically setting servlet config init-param pairs in the vaadin 7 environment would be most useful? Possibly worth adding into the book!