anchor.diff:    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
  -  ].
  +  [v0_9, v0_10, v0_11, v1_0, v2_0, v2_1, v2_2, v2_3, v2_4].
   
   max_vsn(v0_9) -> max_vsn(v0_10);
   max_vsn(v0_10) ->
  
positive.code:                           [ {group_id, GroupId}
                            , {generation_id, Generation}
                            , {member_id, MemberId}
                            ]),
    SendFun =
      fun() ->
  
negative.code: leave_group(Connection, GroupId, MemberId, KafkaVsn) ->
    Fields = #{ group_id => GroupId
              , member_id => MemberId
                %% members field since 2.3
              , members => [#{member_id => MemberId,
                              group_instance_id => ?STATIC_MEMBER_ID
                             }]
              },
    Rsp = request_sync(Connection, leave_group, Fields, KafkaVsn),
    ?assertMatch(#{error_code := no_error}, Rsp),
  