Keycloak API UserRepresentation.getgroups always null

When Using the API (17.0.1) and call either :, true) or

i get a UserRepresentation object.
Eventhough the found users are part of a group the groups (List) field is null.

When I call UsersResource.get(id).groups() i do see them.

How can i make sure that the UserRepresentation.groups field isn’t null