minor #16465 [Messenger] Correct PHP Code block for messenger resetOnMessage (PhilETaylor)

This PR was merged into the 5.4 branch.

Discussion
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[Messenger] Correct PHP Code block for messenger resetOnMessage

This PHP code was incorrect. See the yaml and the XML and compare with the PHP and you can see that (or waste 30 mins like I did debugging to work it out haha)

the method needs to be called on the MessengerConfig object and not chained after a dsn call, which will just give an undefined method error.

Commits
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428a0df Correct PHP Code block for messenger resetOnMessage

Author: javiereguiluz

messenger.rst

@@ -768,10 +768,7 @@ reset the service container between two messages:
         return static function (FrameworkConfig $framework) {
             $messenger = $framework->messenger();
 
-            $messenger->transport('async')
-                ->dsn('%env(MESSENGER_TRANSPORT_DSN)%')
-                ->resetOnMessage(true)
-            ;
+            $messenger->resetOnMessage(true);
         };
 
 .. versionadded:: 5.4