Request parameter get lost when forwarding from one servlet to another

Hi,

I think I've found a bug in the servlet extension of guice.
In a servlet, I'm forwarding the request to another servlet.

I've mapped to servlets:

```
serve("/", "/index.jsp").with(MainEntryServlet.class);
serve("/foobar.jsp").with(FooBarServlet.class);
```

I'm using the following code in my FooBar-Servlet:

```
String url = "/index.jsp?target=foo.jsp";
request.getRequestDispatcher(url).forward(request, response);
```

The MainEntryServlet gets called, but the paramter "target" is missing.
When I use the web.xml for servlet mapping, everything works fine.

Any idea, why the paramater gets lost, when mapping the servlets in the servlet module?