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Similarly for "List of voter groups" and "List of result viewer groups" (for both the Survey and Vote macros).
DO YOU REALLY NEED TO FIND AND EDIT ALL OF YOUR SURVEY/VOTE MACROS?
Not really. The most complete solution would be to find them all and to move usernames out of the groupname parameters to the new username parameters, as described earlier (again, only necessary if the macro is combining usernames and groupnames in the parameters which is rare in practice). The other alternative is to ignore the issue, do the upgrade, and see if any users are denied access to a survey/vote that they need access to. That might not sound like a great solution but it is not a dangerous solution.
For a huge site where you have many page authors and you don’t really know how many of the survey/vote macros are combining usernames and groupnames in the parameters you could do the searches to find them all but do you really need to do that?
If you choose to ignore it, do the upgrade, and wait to see what happens: It is safe to do it that way because any survey/vote macro that is currently combining usernames and groupnames in a restriction parameter will start to deny access to the users whose usernames are listed in the groupname parameters. They will no longer be able to participate in the vote/survey. That is not ideal, but it is not a security problem, it does not open up any survey/vote to anyone who should not have access. If a user can't vote or can’t manage a survey then that is something that is easy to detect because the user will know right away and the page owners will probably find out quickly after that.