Today, we have to do :
Filter f = this.getSession().getEnabledFilter("myFilter");
String currentLocale = (String) ((FilterImpl)f).getParameter("currentLocale"); //here is an "horrible" cast
this.getSession().disableFilter("myFilter");
/do something in session without the filter/
f = this.getSession().enableFilter("myFilter");
f.setParameter("currentLocale", currentLocale);
f.validate();