I use the same filter, with no problems. However, my web.xml is
probably configured a little differently:
I remember from where I got that filter, it just applied it to every
request.
Instead of that, I only apply the filter to URLs that end in
nocache.js like so - (note the url-pattern)
<filter>
<filter-name>NoCache</filter-name>
<filter-class>com.whatever.web.GWTCacheControlFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>NoCache</filter-name>
<url-pattern>*nocache.js</url-pattern>
</filter-mapping>