add broker object to stake holder serializer

apps/pos_device/web/api/v1/serilaizers/device.py

@@ -93,6 +93,12 @@ class StakeHoldersSerializer(ModelSerializer):
             'id': instance.organization.id
         }
 
+        if instance.broker:
+            representation['broker'] = {
+                'name': instance.broker.name,
+                'id': instance.broker.id
+            }
+
         return representation