CA to block downgrades. Possible?

[cubt85iz]

Ran into the issue discussed in Eps 4-6 of Deployment Dojo series and I'm trying to figure if there's a way to workaround the issue using a CustomAction. I've got an action defined that's firing after FindRelatedProducts action, but the ProductVersion shown is the current version, not the one being installed. Anyone know if it's possible to get the ProductVersion of the installer in the customaction before any changes are committed? Thanks.

      [CustomAction]
      public static ActionResult ProhibitInstall(Session session)
      {
         ActionResult result = ActionResult.Success;

         session.Log($"UPGRADINGPRODUCTCODE: {session["UPGRADINGPRODUCTCODE"]}");
         session.Log($"ProductCode: {session["ProductCode"]}");
         session.Log($"ProductVersion: {session["ProductVersion"]}");

         if (IsOlderInstaller(session))
         {
            result = ActionResult.Failure;
         }

         return result;

      }