At http://wiki.opensymphony.com/display/WW/url, is stated includeParams attribute is "get" by default, indeed it was on 2.2.1.
On 2.2.2 the ww url tag stop to work properly, tracking down the issue I found out includeParams attribute needed to be "get" or "all" to work
See attached the test case.
1) unzip it and copy the directory "ww-222-url-bug" to $CATALINA_HOME/webapps, restart tomcat
2) open the browser and points to http://localhost:8080/ww-222-url-bug/encodingTestNew.action
3) submit anything
4) click at the link "Correct some fields"
5) the previous form is not filled
The scope interceptor is used.
To make it work
Edit encoding_test_2.ftl and add the attribute includeParams="get", make the test again.