override group adapters

src/redturtle/volto/restapi/serializer/configure.zcml

@@ -30,4 +30,6 @@
     <adapter factory=".collection.SerializeCollectionToJson" />
   </configure>
 
+  <adapter factory=".group.SerializeGroupToJson" />
+
 </configure>

src/redturtle/volto/restapi/serializer/group.py

@@ -0,0 +1,39 @@
+from plone.restapi.batching import HypermediaBatch
+from plone.restapi.interfaces import ISerializeToJson
+from Products.PlonePAS.interfaces.group import IGroupData
+from zope.component import adapter
+from zope.interface import implementer
+from redturtle.volto.interfaces import IRedturtleVoltoLayer
+from Products.PluggableAuthService.interfaces.plugins import IRolesPlugin
+from plone.restapi.serializer.group import BaseSerializer
+from plone import api
+
+
+@implementer(ISerializeToJson)
+@adapter(IGroupData, IRedturtleVoltoLayer)
+class SerializeGroupToJson(BaseSerializer):
+    def __call__(self):
+        data = super().__call__()
+        group = self.context
+        if group.id == 'AuthenticatedUsers':
+            data['roles'] = []
+            acl = api.portal.get_tool('acl_users')
+            rolemakers = acl.plugins.listPlugins(IRolesPlugin)
+            for rolemaker_id, rolemaker in rolemakers:
+                roles = rolemaker.getRolesForPrincipal(group) or ()
+                data['roles'].extend(roles)
+
+        members = group.getGroupMemberIds()
+        batch = HypermediaBatch(self.request, members)
+        members_data = {
+            "@id": batch.canonical_url,
+            "items_total": batch.items_total,
+            "items": sorted(batch),
+        }
+        if batch.links:
+            members_data["batching"] = batch.links
+
+        data["members"] = members_data
+        return data
+
+