We should add a method refresh() to the resource resolver which delegates this call to all resource providers implementing the RefreshableResourceProvider (or is there a better name?)
Some data storages like JCR (especially with the upcoming Oak implementation) might give you the state of the storage from the time the login happened. Therefore we need a way to get the latest state. In JCR this is done through the refresh method. With adding this for resource providers we can support this for all resource providers.