We have a page that presents a report in which we can "drill down" into the data. When this happens, we setResponsePage() back to a new instance of the page with some different parameters and that all works dandy. But when we hit the back button, it seems the old version is gone. All the model data comes back null (though the model object itself is not). So when we click back and then click another link to drilldown in another direction we get NPEs. From stepping through DiskPageStore, et. al, it would appear that since the page class isn't changing, the new page bumps the old one from the cache so that only one version of the page.
Am I correctly interpreting what I'm seeing and is there a way to set the number of versions of a page?
