Merge pull request #336599 from bjornfor/nixos-ups-use-enum-for-upsmon-option

      };

      upsmon = mkOption {

        type = with types; nullOr str;

        type = with types; nullOr (enum [ "primary" "secondary" ]);

        default = null;

        description = ''

          Add the necessary actions for a upsmon process to work.