Add ReasonCode to SendExtendedAuthenticationExchangeDataAsync (#1882)

* add reason code to ext auth

* Update ReleaseNotes.md

---------

Co-authored-by: Christian <6939810+chkr1011@users.noreply.github.com>

Author: rido-min

.github/workflows/ReleaseNotes.md

@@ -1,3 +1,4 @@
 * [Server] Fixed not working _UpdateRetainedMessageAsync_ public api (#1858, thanks to @kimdiego2098).
 * [Client] Added support for custom CA chain validation (#1851, thanks to @rido-min).
-* [Client] Fixed handling of unobserved tasks exceptions (#1871).
+* [Client] Fixed handling of unobserved tasks exceptions (#1871).
+* [Client] Fixed not specified ReasonCode when using _SendExtendedAuthenticationExchangeDataAsync_ (#1882, thanks to @rido-min).

Source/MQTTnet/Client/MqttClient.cs

@@ -309,6 +309,7 @@ public Task SendExtendedAuthenticationExchangeDataAsync(MqttExtendedAuthenticati
                 AuthenticationMethod = Options.AuthenticationMethod,
                 AuthenticationData = data.AuthenticationData,
                 ReasonString = data.ReasonString,
+                ReasonCode = data.ReasonCode,
                 UserProperties = data.UserProperties
             };