[keycloak-user] Client Mapper mutiple value

Hi, i specified a user attribute mapper for a client and set Multivalued to true. The values i want to map are attributes specified in groups. The idea is to collect the attributes with the same name in all groups and make them available as list in the tokens. When i use the mapper i can see a value of one group but not the values of other groups. When the mapper does not collect the attributes from all groups what is the purpose of the multivalued flag? I cannot specify more than one attribute with the same name in the user or in one group so i never see mutiple values. Thanks Best regards Denny