code: def upgradePrivateApplication4to5(old):
      
      new = old.upgradeVersion(
          PrivateApplication.typeName, 4, 5,
          preferredTheme=old.preferredTheme,
          privateKey=old.privateKey,
          website=old.website,
          customizedPublicPage=old.customizedPublicPage,
          authenticationApplication=old.authenticationApplication,
          preferenceAggregator=old.preferenceAggregator,
          defaultPreferenceCollection=old.defaultPreferenceCollection,
          searchAggregator=old.searchAggregator)
      new.store.powerUp(new, IWebViewer)
      return new
docs: Install the newly required powerup.