@RequirePOST
    public HttpResponse doUpgrade(StaplerRequest req, StaplerResponse rsp) {
        final String thruVerParam = req.getParameter("thruVer");
        final VersionNumber thruVer = thruVerParam.equals("all") ? null : new VersionNumber(thruVerParam);

        saveAndRemoveEntries(new Predicate<Map.Entry<SaveableReference, VersionRange>>() {
            @Override
            public boolean apply(Map.Entry<SaveableReference, VersionRange> entry) {
                VersionNumber version = entry.getValue().max;
                return version != null && (thruVer == null || !version.isNewerThan(thruVer));
            }
        });

        return HttpResponses.forwardToPreviousPage();
    }
@ RequirePOST public HttpResponse doUpgrade ( StaplerRequest req , StaplerResponse rsp ) { final String thruVerParam = req . getParameter ( "thruVer" ) ; final VersionNumber thruVer = thruVerParam . equals ( "all" ) ? null : new VersionNumber ( thruVerParam ) ; saveAndRemoveEntries ( new Predicate < Map . Entry < SaveableReference , VersionRange > > ( ) { @ Override public boolean apply ( Map . Entry < SaveableReference , VersionRange > entry ) { VersionNumber version = entry . getValue ( ) . max ; return version != null && ( thruVer == null || ! version . isNewerThan ( thruVer ) ) ; } } ) ; return HttpResponses . forwardToPreviousPage ( ) ; }
Save all or some of the files to persist data in the new forms.
Remove those items from the data map.