anchor.diff:  %%%_* APIs for group coordinator ===============================================
   
   %% @doc Called by group coordinator when there is new assignemnt received.
  --spec assignments_received(pid(), member_id(), integer(),
  -                           brod_received_assignments()) -> ok.
  +-spec assignments_received(pid(), brod:member_id(), integer(),
  +                           brod:brod_received_assignments()) -> ok.
   assignments_received(Pid, MemberId, GenerationId, TopicAssignments) ->
     gen_server:cast(Pid, {new_assignments, MemberId,
                           GenerationId, TopicAssignments}).
  
positive.code: %% NOTE: this function is called only when it is DISABLED to commit offsets
  %%       to kafka.
  %% @end
  -spec get_committed_offsets(pid(), [{topic(), partition()}]) ->
          {ok, [{{topic(), partition()}, offset()}]}.
  get_committed_offsets(Pid, TopicPartitions) ->
    gen_server:call(Pid, {get_committed_offsets, TopicPartitions}, infinity).
  
  
negative.code: %% partition-consumers are fetching more messages behind the scene
  %% unless prefetch_count is set to 0 in consumer config.
  %%
  -callback handle_message(brod:topic(), brod:partition(), #kafka_message{}, cb_state()) ->
              {ok, cb_state()} | {ok, ack, cb_state()}.
  
  %% This callback is called only when subscriber is to commit offsets locally
  