Restore support for null in _AddServer_ method in ASP.NET integration (#1981)

* Upgrade ASP test project to dotnet8.

* Fix broken null support for _AddMqttServer_ method.

* Fix wrong code style

* Downgrade to dotnet7.0

* Expose certificate selection in MQTTnet options

* Revert "Expose certificate selection in MQTTnet options"

This reverts commit f7d098a119.

* Update release notes

.editorconfig

@@ -40,7 +40,6 @@ dotnet_style_qualification_for_method = false:suggestion
 dotnet_style_qualification_for_property = false:suggestion
 
 # ReSharper properties
-resharper_autodetect_indent_settings = true
 resharper_default_private_modifier = implicit
 resharper_place_accessorholder_attribute_on_same_line = false
 resharper_use_indent_from_vs = false
@@ -61,7 +60,7 @@ resharper_web_config_wrong_module_highlighting = warning
 [*]
 charset = utf-8
 end_of_line = crlf
-trim_trailing_whitespace = false
+trim_trailing_whitespace = true
 insert_final_newline = false
 indent_style = space
 indent_size = 4

.github/workflows/ReleaseNotes.md

@@ -1,6 +1,7 @@
 * [Core] Optimized packet serialization of PUBACK and PUBREC packets for protocol version 5.0.0 (#1939, thanks to @Y-Sindo).
 * [Core] The package inspector is now fully async (#1941).
 * [Client] Added a dedicated exception when the client is not connected (#1954, thanks to @marcpiulachs).
-* [Server] The server will no longer send _NoMatchingSubscribers_ when the actual subscription was non success (#1965, BREAKING CHANGE!). 
+* [Server] The server will no longer send _NoMatchingSubscribers_ when the actual subscription was non success (#1965, BREAKING CHANGE!).
+* [Server] Fixed broken support for _null_ in _AddServer_ method in ASP.NET integration (#1981).
 * [ManagedClient] Added a new event (SubscriptionsChangedAsync) which is fired when a subscription or unsubscription was made (#1894, thanks to @pdufrene).
 * [TopicTemplate] Added new extension which provides a template engine for topics (#1932, thanks to @simonthum).

Source/MQTTnet.AspTestApp/MQTTnet.AspTestApp.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk.Web">
 
     <PropertyGroup>
-        <TargetFramework>net6.0</TargetFramework>
+        <TargetFramework>net7.0</TargetFramework>
         <Nullable>enable</Nullable>
         <ImplicitUsings>enable</ImplicitUsings>
         <IsPackable>false</IsPackable>

Source/MQTTnet.AspnetCore/ServiceCollectionExtensions.cs

@@ -40,13 +40,10 @@ namespace MQTTnet.AspNetCore
                 throw new ArgumentNullException(nameof(services));
             }
 
-            if (configure == null)
-            {
-                throw new ArgumentNullException(nameof(configure));
-            }
-
             var serverOptionsBuilder = new MqttServerOptionsBuilder();
-            configure.Invoke(serverOptionsBuilder);
+
+            configure?.Invoke(serverOptionsBuilder);
+
             var options = serverOptionsBuilder.Build();
 
             return AddHostedMqttServer(services, options);