Set AMQP rejected error description

 ### What?
This commit is a follow-up to #15075
setting the `description` field of the AMQP `error` if RabbitMQ rejects
a message.

 ### Why?
Client libs can then just pass this error description string to client
apps, which in turn could optionally log that message.

Author: ansd

deps/rabbit/src/rabbit_amqp_session.erl

@@ -697,12 +697,14 @@ send_delivery_state_changes(State0 = #state{cfg = #cfg{writer_pid = Writer,
     {RejectedIds, GrantCredits0, State1} = handle_stashed_rejected(State0),
     maps:foreach(
       fun({QNameBin, Reason}, Ids) ->
+              Description = reject_description(QNameBin, Reason),
               Info = {map,
                       [{{symbol, <<"queue">>}, {utf8, QNameBin}},
                        {{symbol, <<"reason">>}, {symbol, reject_reason_to_binary(Reason)}}]},
               Rej = #'v1_0.rejected'{
                        error = #'v1_0.error'{
                                   condition = ?V_1_0_AMQP_ERROR_PRECONDITION_FAILED,
+                                  description = {utf8, Description},
                                   info = Info}},
               send_dispositions(Ids, Rej, Writer, ChannelNum)
       end, RejectedIds),
@@ -2603,6 +2605,11 @@ rejected(DeliveryId, Error) ->
                         settled = true,
                         state = #'v1_0.rejected'{error = Error}}.
 
+reject_description(QNameBin, maxlen) ->
+    <<"queue '", QNameBin/binary, "' exceeded maximum length">>;
+reject_description(QNameBin, down) ->
+    <<"queue '", QNameBin/binary, "' is unavailable">>.
+
 reject_reason_to_binary(maxlen) ->
     <<"maxlen">>;
 reject_reason_to_binary(down) ->

deps/rabbit/test/amqp_client_SUITE.erl

@@ -3607,8 +3607,10 @@ target_quorum_queue_rejects(Config) ->
     ok = amqp10_client:send_msg(Sender, amqp10_msg:new(<<"tag d">>, <<>>, false)),
 
     [receive {amqp10_disposition, {{rejected, Error}, DTag}} ->
-                 ?assertMatch(
+                 ?assertEqual(
                     #'v1_0.error'{
+                       condition = ?V_1_0_AMQP_ERROR_PRECONDITION_FAILED,
+                       description = {utf8, <<"queue '🎄' exceeded maximum length"/utf8>>},
                        info = {map, [{{symbol, <<"queue">>}, {utf8, QName}},
                                      {{symbol, <<"reason">>}, {symbol, <<"maxlen">>}}]}},
                     Error)
@@ -3667,6 +3669,7 @@ target_classic_queue_rejects(Config) ->
     ok = amqp10_client:send_msg(Sender, amqp10_msg:new(<<"t2">>, <<"m2">>)),
     ExpectedErr1 = #'v1_0.error'{
                       condition = ?V_1_0_AMQP_ERROR_PRECONDITION_FAILED,
+                      description = {utf8, <<"queue '", QName1/binary, "' exceeded maximum length">>},
                       info = {map, [{{symbol, <<"queue">>}, {utf8, QName1}},
                                     {{symbol, <<"reason">>}, {symbol, <<"maxlen">>}}]}},
     ok = wait_for_settlement(<<"t2">>, {rejected, ExpectedErr1}),
@@ -3693,6 +3696,7 @@ target_classic_queue_rejects(Config) ->
     ok = amqp10_client:send_msg(Sender, amqp10_msg:new(<<"t3">>, <<"m3">>)),
     ExpectedErr3 = #'v1_0.error'{
                       condition = ?V_1_0_AMQP_ERROR_PRECONDITION_FAILED,
+                      description = {utf8, <<"queue '", QName2/binary, "' is unavailable">>},
                       info = {map, [{{symbol, <<"queue">>}, {utf8, QName2}},
                                     {{symbol, <<"reason">>}, {symbol, <<"unavailable">>}}]}},
     ok = wait_for_settlement(<<"t3">>, {rejected, ExpectedErr3}),