Sprint Gadget shall allow specification of closed sprints

The Gadgets "Sprint Burndown" and "Sprint Health" allow to specify which sprint to show. However, only active sprints are shown for selection (which is a useless selection, since for one team, we have only one active Sprint). The Gadgets are used to document specific sprints in Confluence (one ConfluencePage per sprint), the currenct behaviour renders the Gadget useless, since the page exhibits a space with an error message, once the sprint is finished (see atached screenshot). It should show the statistics of the selected sprint, even if its finished (like in the sprint report, where finished sprints can be seleted).