Why does spring-ws 2.2.0 depends on servlet spec 3.0?

I need to upgrade to spring-ws 2.2.0 in order to take advantage of the new annotation @PayloadRoot for mapping multiple requests to the same endpoint method. But I noticed in the POM that spring-ws 2.2.0 depends on the servlet spec 3.0.1. Currently not all of our web servers support servlet spec 3.0 yet.

I built my code with spring-ws 2.2.0 and deployed to Tomcat 6.x, which only supports servlet spec 2.5, everything seemed to work fine so far.

So my questions are: why does spring-ws 2.2.0 depends on servlet spec 3.0? What could happen if I run it against servlet spec 2.5? Could I get away with not upgrading web servers to get servlet spec 3.0 support? The reason I'm asking these questions is that it could be a hassle to upgrade all the web server versions in a short period of time in a corporate environment.

Thanks for help.