treewide: use attrs instead of list for types.loaOf options

nixos/modules/services/search/hound.nix

@@ -88,19 +88,19 @@ in {
   };
 
   config = mkIf cfg.enable {
-    users.groups = optional (cfg.group == "hound") {
-      name = "hound";
-      gid = config.ids.gids.hound;
+    users.groups = optionalAttrs (cfg.group == "hound") {
+      hound.gid = config.ids.gids.hound;
     };
 
-    users.users = optional (cfg.user == "hound") {
-      name = "hound";
-      description = "hound code search";
-      createHome = true;
-      home = cfg.home;
-      group = cfg.group;
-      extraGroups = cfg.extraGroups;
-      uid = config.ids.uids.hound;
+    users.users = optionalAttrs (cfg.user == "hound") {
+      hound = {
+        description = "hound code search";
+        createHome = true;
+        home = cfg.home;
+        group = cfg.group;
+        extraGroups = cfg.extraGroups;
+        uid = config.ids.uids.hound;
+      };
     };
 
     systemd.services.hound = {

nixos/modules/services/search/kibana.nix

@@ -198,8 +198,7 @@ in {
 
     environment.systemPackages = [ cfg.package ];
 
-    users.users = singleton {
-      name = "kibana";
+    users.users.kibana = {
       uid = config.ids.uids.kibana;
       description = "Kibana service user";
       home = cfg.dataDir;

nixos/modules/services/search/solr.nix

@@ -100,18 +100,18 @@ in
       };
     };
 
-    users.users = optionalAttrs (cfg.user == "solr") (singleton
-      { name = "solr";
+    users.users = optionalAttrs (cfg.user == "solr") {
+      solr = {
         group = cfg.group;
         home = cfg.stateDir;
         createHome = true;
         uid = config.ids.uids.solr;
-      });
+      };
+    };
 
-    users.groups = optionalAttrs (cfg.group == "solr") (singleton
-      { name = "solr";
-        gid = config.ids.gids.solr;
-      });
+    users.groups = optionalAttrs (cfg.group == "solr") {
+      solr.gid = config.ids.gids.solr;
+    };
 
   };