Fix crash when closing connection

Avoid the following crash ``` ** Reason for termination == ** {mqtt_unexpected_cast,{shutdown,"Closed via management plugin"}} crasher: initial call: rabbit_mqtt_reader:init/1 pid: <0.1096.0> registered_name: [] exception exit: {mqtt_unexpected_cast, {shutdown,"Closed via management plugin"}} in function gen_server:handle_common_reply/8 (gen_server.erl, line 1208) ``` when closing MQTT or Stream connections via HTTP API endpoint ``` /connections/username/:username ```

Author: ansd

deps/rabbitmq_management/src/rabbit_mgmt_wm_connection_user_name.erl

@@ -85,7 +85,8 @@ force_close_connection(ReqData, Conn, Pid) ->
  network ->
  rabbit_networking:close_connection(Pid, Reason);
  _ ->
- % best effort, this will work for connections to the stream plugin
- gen_server:cast(Pid, {shutdown, Reason})
- end,
- ok.
+ %% Best effort will work for following plugins:
+ %% rabbitmq_stream, rabbitmq_mqtt, rabbitmq_web_mqtt
+ _ = Pid ! {shutdown, Reason},
+ ok
+ end.

deps/rabbitmq_mqtt/test/shared_SUITE.erl

@@ -1217,19 +1217,27 @@ management_plugin_connection(Config) ->
  KeepaliveSecs = 99,
  ClientId = atom_to_binary(?FUNCTION_NAME),
  Node = atom_to_binary(get_node_config(Config, 0, nodename)),
- C = connect(ClientId, Config, [{keepalive, KeepaliveSecs}]),
 
+ C1 = connect(ClientId, Config, [{keepalive, KeepaliveSecs}]),
  eventually(?_assertEqual(1, length(http_get(Config, "/connections"))), 1000, 10),
  [#{client_properties := #{client_id := ClientId},
  timeout := KeepaliveSecs,
  node := Node,
  name := ConnectionName}] = http_get(Config, "/connections"),
-
  process_flag(trap_exit, true),
  http_delete(Config,
  "/connections/" ++ binary_to_list(uri_string:quote((ConnectionName))),
  ?NO_CONTENT),
- await_exit(C),
+ await_exit(C1),
+ ?assertEqual([], http_get(Config, "/connections")),
+ eventually(?_assertEqual([], all_connection_pids(Config)), 500, 3),
+
+ C2 = connect(ClientId, Config, [{keepalive, KeepaliveSecs}]),
+ eventually(?_assertEqual(1, length(http_get(Config, "/connections"))), 1000, 10),
+ http_delete(Config,
+ "/connections/username/guest",
+ ?NO_CONTENT),
+ await_exit(C2),
  ?assertEqual([], http_get(Config, "/connections")),
  eventually(?_assertEqual([], all_connection_pids(Config)), 500, 3).