should return the real path of the WEB-INF directory for your web-app.
Based on that you should be able to find the directory you need.
It works on Tomcat, and will likely fail miserably on Novel Extends (SilverStream) as the latter does not use a filesystem to store files.
Anybody's guess what it will return (and what will happen if you try to write there) if your webapp is contained in a packaged (meaning not expanded at deployment time) warfile.
Might be interesting to try