Which jar for multipartfilter?

[Patrick Haggood]

I've checked my webapp's WEB-INF/lib folder, myfaces.jar and
myfaces-extensions.jar are both there.  I even copied them to tomcat's
common/lib to be sure.  Still getting the following error:  

SEVERE: Exception starting filter multipartFilter
java.lang.ClassNotFoundException:
net.sourceforge.myfaces.custom.fileupload.ExtensionsFilter
        at
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1332)