anchor.diff:  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),
  
positive.code: 
  -define(TIMEOUT, 10000).
  -define(TOPIC, <<"t1">>).
  
  %% A typical group member live-cycle:
  %% 1. find_coordinator, to figure out which broker to connect to
  
negative.code:   I.
  
  kafka_vsns() ->
    [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) ->
  