anchor.diff:                            [ {group_id, GroupId}
                             , {generation_id, Generation}
                             , {member_id, MemberId}
  +                          , {group_instance_id, ?STATIC_MEMBER_ID}
                             ]),
     SendFun =
       fun() ->
  
positive.code:   I.
  
  kafka_vsns() ->
    [v0_9, v0_10, v0_11, v1_0, v2_0, v2_1, v2_2
     %%,v2_3, v2_4 % commented out, TODO: test group_instance_id
    ].
  
  max_vsn(v0_9) -> max_vsn(v0_10);
  max_vsn(v0_10) ->
  
negative.code: 
  test_full_flow(KafkaVsn) ->
    GroupId = make_group_id(full_flow_test),
    StaticMemberID = ?STATIC_MEMBER_ID,
    % find_coordinator (group)
    {ok, Connection} = connect_coordinator(GroupId),
    % join_group
  