diff --git a/lib/plankton/plankton.d.ts b/lib/plankton/plankton.d.ts
index 49fd537..d07a527 100644
--- a/lib/plankton/plankton.d.ts
+++ b/lib/plankton/plankton.d.ts
@@ -658,6 +658,9 @@ declare namespace lib_plankton.call {
     /**
      */
     export function sleep(seconds: float): Promise<void>;
+    /**
+     */
+    export function null_prop<type_value_from, type_value_to>(value_from: (null | type_value_from), function_: ((value: type_value_from) => type_value_to)): (null | type_value_to);
     export {};
 }
 declare namespace lib_plankton.email {
@@ -4598,6 +4601,7 @@ declare namespace lib_plankton.auth.oidc {
         name: (null | string);
         label: (null | string);
         email: (null | string);
+        groups: (null | Array<string>);
     };
     /**
      */
diff --git a/lib/plankton/plankton.js b/lib/plankton/plankton.js
index 2232892..3cf2c27 100644
--- a/lib/plankton/plankton.js
+++ b/lib/plankton/plankton.js
@@ -1491,6 +1491,16 @@ var lib_plankton;
             }));
         }
         call.sleep = sleep;
+        /**
+         */
+        function null_prop(value_from, function_) {
+            return ((value_from === null)
+                ?
+                    null
+                :
+                    function_(value_from));
+        }
+        call.null_prop = null_prop;
     })(call = lib_plankton.call || (lib_plankton.call = {}));
 })(lib_plankton || (lib_plankton = {}));
 var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
@@ -4056,10 +4066,10 @@ var lib_plankton;
             options = Object.assign({
                 "compare_value": instance_compare
             }, options);
-            if (is_empty(list)) {
+            /*if (is_empty<type_element>(list)) {
                 throw (new Error("the max-arg of an empty list is not defined"));
             }
-            else {
+            else */ {
                 return (list
                     .reduce(function (result, element, index) {
                     var value = target_function(element);
@@ -14466,8 +14476,7 @@ var lib_plankton;
                         }
                     };
                     lib_plankton.log.info("plankton.server.client_connected");
-                    socket.on("data", (input_chunk_raw, x2, x3, x4, x5) => {
-                        process.stderr.write(JSON.stringify({ x2, x3, x4, x5 }) + "\n");
+                    socket.on("data", (input_chunk_raw) => {
                         lib_plankton.log.debug("plankton.server.reading_chunk", {
                             "chunk_raw": ((input_chunk_raw instanceof Buffer)
                                 ?
@@ -16231,6 +16240,11 @@ var lib_plankton;
                     "name": (data["preferred_username"] ?? null),
                     "label": (data["name"] ?? null),
                     "email": (data["email"] ?? null),
+                    "groups": (((data["groups"] === undefined) || (data["groups"] === null))
+                        ?
+                            null
+                        :
+                            data["groups"].split(",")),
                 });
             }
             /**
diff --git a/source/value_objects/access_level.ts b/source/value_objects/access_level.ts
deleted file mode 100644
index d1a5168..0000000
--- a/source/value_objects/access_level.ts
+++ /dev/null
@@ -1,74 +0,0 @@
-/*
-This file is part of »zeitbild«.
-
-Copyright 2025 'kcf' <fenris@folksprak.org>
-
-»zeitbild« is free software: you can redistribute it and/or modify
-it under the terms of the GNU Lesser General Public License as published by
-the Free Software Foundation, either version 3 of the License, or
-(at your option) any later version.
-
-»zeitbild« is distributed in the hope that it will be useful,
-but WITHOUT ANY WARRANTY; without even the implied warranty of
-MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-GNU Lesser General Public License for more details.
-
-You should have received a copy of the GNU Lesser General Public License
-along with »zeitbild«. If not, see <http://www.gnu.org/licenses/>.
- */
-
-
-/**
- */
-namespace _zeitbild.value_object.access_level
-{
-	
-	/**
-	 */
-	export function to_string(
-		access_level : _zeitbild.enum_access_level
-	) : string
-	{
-		switch (access_level) {
-			case _zeitbild.enum_access_level.none: {return "none";}
-			case _zeitbild.enum_access_level.view: {return "view";}
-			case _zeitbild.enum_access_level.edit: {return "edit";}
-			case _zeitbild.enum_access_level.admin: {return "admin";}
-			default: {throw (new Error("invalid access level: " + String(access_level)));}
-		}
-	}
-	
-	
-	/**
-	 */
-	export function from_string(
-		access_level_ : string
-	) : _zeitbild.enum_access_level
-	{
-		switch (access_level_) {
-			case "none": {return _zeitbild.enum_access_level.none;}
-			case "view": {return _zeitbild.enum_access_level.view;}
-			case "edit": {return _zeitbild.enum_access_level.edit;}
-			case "admin": {return _zeitbild.enum_access_level.admin;}
-			default: {throw (new Error("invalid encoded access level: " + String(access_level_)));}
-		}
-	}
-	
-	
-	/**
-	 */
-	export function order(
-		x : _zeitbild.enum_access_level,
-		y : _zeitbild.enum_access_level
-	) : boolean
-	{
-		const list : Array<_zeitbild.enum_access_level> = [
-			_zeitbild.enum_access_level.none,
-			_zeitbild.enum_access_level.view,
-			_zeitbild.enum_access_level.edit,
-			_zeitbild.enum_access_level.admin,
-		];
-		return (list.indexOf(x) <= list.indexOf(y));
-	}
-	
-}