Convert null checks to modern ThrowIfNull checks (#2089)

Convert null check to modern ThrowIfNull checks

Samples/Server/Server_Retained_Messages_Samples.cs

@@ -102,10 +102,7 @@ public static class Server_Retained_Messages_Samples
 
         public static MqttRetainedMessageModel Create(MqttApplicationMessage message)
         {
-            if (message == null)
+            ArgumentNullException.ThrowIfNull(message);
-            {
-                throw new ArgumentNullException(nameof(message));
-            }
 
             return new MqttRetainedMessageModel
             {

Source/MQTTnet.AspnetCore/EndpointRouterExtensions.cs

@@ -12,10 +12,7 @@ namespace MQTTnet.AspNetCore
     {
         public static void MapMqtt(this IEndpointRouteBuilder endpoints, string pattern)
         {
-            if (endpoints == null)
+            ArgumentNullException.ThrowIfNull(endpoints);
-            {
-                throw new ArgumentNullException(nameof(endpoints));
-            }
 
             endpoints.MapConnectionHandler<MqttConnectionHandler>(pattern, options =>
             {

Source/MQTTnet.AspnetCore/MqttSubProtocolSelector.cs

@@ -13,10 +13,7 @@ public static class MqttSubProtocolSelector
 {
     public static string SelectSubProtocol(HttpRequest request)
     {
-        if (request == null)
+        ArgumentNullException.ThrowIfNull(request);
-        {
-            throw new ArgumentNullException(nameof(request));
-        }
 
         string subProtocol = null;
         if (request.Headers.TryGetValue("Sec-WebSocket-Protocol", out var requestedSubProtocolValues))
@@ -29,10 +26,7 @@ public static class MqttSubProtocolSelector
 
     public static string SelectSubProtocol(IList<string> requestedSubProtocolValues)
     {
-        if (requestedSubProtocolValues == null)
+        ArgumentNullException.ThrowIfNull(requestedSubProtocolValues);
-        {
-            throw new ArgumentNullException(nameof(requestedSubProtocolValues));
-        }
 
         // Order the protocols to also match "mqtt", "mqttv-3.1", "mqttv-3.11" etc.
         return requestedSubProtocolValues.OrderByDescending(p => p.Length).FirstOrDefault(p => p.ToLower().StartsWith("mqtt"));

Source/MQTTnet.AspnetCore/MqttWebSocketServerAdapter.cs

@@ -26,10 +26,7 @@ public sealed class MqttWebSocketServerAdapter : IMqttServerAdapter
 
     public async Task RunWebSocketConnectionAsync(WebSocket webSocket, HttpContext httpContext)
     {
-        if (webSocket == null)
+        ArgumentNullException.ThrowIfNull(webSocket);
-        {
-            throw new ArgumentNullException(nameof(webSocket));
-        }
 
         var endpoint = $"{httpContext.Connection.RemoteIpAddress}:{httpContext.Connection.RemotePort}";
 

Source/MQTTnet.AspnetCore/ReaderExtensions.cs

@@ -22,10 +22,7 @@ public static class ReaderExtensions
         out SequencePosition observed,
         out int bytesRead)
     {
-        if (formatter == null)
+        ArgumentNullException.ThrowIfNull(formatter);
-        {
-            throw new ArgumentNullException(nameof(formatter));
-        }
 
         packet = null;
         consumed = input.Start;

Source/MQTTnet.AspnetCore/ServiceCollectionExtensions.cs

@@ -16,15 +16,8 @@ public static class ServiceCollectionExtensions
 {
     public static IServiceCollection AddHostedMqttServer(this IServiceCollection services, MqttServerOptions options)
     {
-        if (services == null)
+        ArgumentNullException.ThrowIfNull(services);
-        {
+        ArgumentNullException.ThrowIfNull(options);
-            throw new ArgumentNullException(nameof(services));
-        }
-
-        if (options == null)
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         services.AddSingleton(options);
         services.AddHostedMqttServer();
@@ -34,10 +27,7 @@ public static class ServiceCollectionExtensions
 
     public static IServiceCollection AddHostedMqttServer(this IServiceCollection services, Action<MqttServerOptionsBuilder> configure)
     {
-        if (services == null)
+        ArgumentNullException.ThrowIfNull(services);
-        {
-            throw new ArgumentNullException(nameof(services));
-        }
 
         var serverOptionsBuilder = new MqttServerOptionsBuilder();
 
@@ -61,10 +51,7 @@ public static class ServiceCollectionExtensions
 
     public static IServiceCollection AddHostedMqttServerWithServices(this IServiceCollection services, Action<AspNetMqttServerOptionsBuilder> configure)
     {
-        if (services == null)
+        ArgumentNullException.ThrowIfNull(services);
-        {
-            throw new ArgumentNullException(nameof(services));
-        }
 
         services.AddSingleton(
             s =>
@@ -89,20 +76,14 @@ public static class ServiceCollectionExtensions
 
     public static void AddMqttLogger(this IServiceCollection services, IMqttNetLogger logger)
     {
-        if (services == null)
+        ArgumentNullException.ThrowIfNull(services);
-        {
-            throw new ArgumentNullException(nameof(services));
-        }
 
         services.AddSingleton(logger);
     }
 
     public static IServiceCollection AddMqttServer(this IServiceCollection serviceCollection, Action<MqttServerOptionsBuilder> configure = null)
     {
-        if (serviceCollection is null)
+        ArgumentNullException.ThrowIfNull(serviceCollection);
-        {
-            throw new ArgumentNullException(nameof(serviceCollection));
-        }
 
         serviceCollection.AddMqttConnectionHandler();
         serviceCollection.AddHostedMqttServer(configure);

Source/MQTTnet.Benchmarks/ReaderExtensionsBenchmark.cs

@@ -145,7 +145,7 @@ namespace MQTTnet.Benchmarks
                 out SequencePosition observed,
                 out int bytesRead)
             {
-                if (formatter == null) throw new ArgumentNullException(nameof(formatter));
+                ArgumentNullException.ThrowIfNull(formatter);
 
                 packet = null;
                 consumed = input.Start;

Source/MQTTnet.Benchmarks/TopicFilterComparerBenchmark.cs

@@ -73,15 +73,8 @@ namespace MQTTnet.Benchmarks
 
         static bool LegacyMethodByStringSplit(string topic, string filter)
         {
-            if (topic == null)
+            ArgumentNullException.ThrowIfNull(topic);
-            {
+            ArgumentNullException.ThrowIfNull(filter);
-                throw new ArgumentNullException(nameof(topic));
-            }
-
-            if (filter == null)
-            {
-                throw new ArgumentNullException(nameof(filter));
-            }
 
             if (string.Equals(topic, filter, StringComparison.Ordinal))
             {

Source/MQTTnet.Extensions.Rpc/DefaultMqttRpcClientTopicGenerationStrategy.cs

@@ -10,10 +10,7 @@ namespace MQTTnet.Extensions.Rpc
     {
         public MqttRpcTopicPair CreateRpcTopics(TopicGenerationContext context)
         {
-            if (context == null)
+            ArgumentNullException.ThrowIfNull(context);
-            {
-                throw new ArgumentNullException(nameof(context));
-            }
 
             if (context.MethodName.Contains("/") || context.MethodName.Contains("+") || context.MethodName.Contains("#"))
             {

Source/MQTTnet.Extensions.Rpc/MqttFactoryExtensions.cs

@@ -20,15 +20,8 @@ namespace MQTTnet.Extensions.Rpc
 
         public static IMqttRpcClient CreateMqttRpcClient(this MqttClientFactory _, IMqttClient mqttClient, MqttRpcClientOptions rpcClientOptions)
         {
-            if (mqttClient == null)
+            ArgumentNullException.ThrowIfNull(mqttClient);
-            {
+            ArgumentNullException.ThrowIfNull(rpcClientOptions);
-                throw new ArgumentNullException(nameof(mqttClient));
-            }
-
-            if (rpcClientOptions == null)
-            {
-                throw new ArgumentNullException(nameof(rpcClientOptions));
-            }
 
             return new MqttRpcClient(mqttClient, rpcClientOptions);
         }

Source/MQTTnet.Extensions.Rpc/MqttRpcClient.cs

@@ -65,10 +65,7 @@ namespace MQTTnet.Extensions.Rpc
 
         public async Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, IDictionary<string, object> parameters = null, CancellationToken cancellationToken = default)
         {
-            if (methodName == null)
+            ArgumentNullException.ThrowIfNull(methodName);
-            {
-                throw new ArgumentNullException(nameof(methodName));
-            }
 
             var context = new TopicGenerationContext(_mqttClient, _options, methodName, parameters, qualityOfServiceLevel);
             var topicNames = _options.TopicGenerationStrategy.CreateRpcTopics(context);

Source/MQTTnet.Extensions.TopicTemplate/MqttTopicTemplate.cs

@@ -41,10 +41,7 @@ public sealed class MqttTopicTemplate : IEquatable<MqttTopicTemplate>
     /// </exception>
     public MqttTopicTemplate(string topicTemplate)
     {
-        if (topicTemplate == null)
+        ArgumentNullException.ThrowIfNull(topicTemplate);
-        {
-            throw new ArgumentNullException(nameof(topicTemplate));
-        }
 
         MqttTopicValidator.ThrowIfInvalidSubscribe(topicTemplate);
 

Source/MQTTnet.Server/Internal/Formatter/MqttConnAckPacketFactory.cs

@@ -12,10 +12,7 @@ public static class MqttConnAckPacketFactory
 {
     public static MqttConnAckPacket Create(ValidatingConnectionEventArgs validatingConnectionEventArgs)
     {
-        if (validatingConnectionEventArgs == null)
+        ArgumentNullException.ThrowIfNull(validatingConnectionEventArgs);
-        {
-            throw new ArgumentNullException(nameof(validatingConnectionEventArgs));
-        }
 
         var connAckPacket = new MqttConnAckPacket
         {

Source/MQTTnet.Server/Internal/Formatter/MqttPubAckPacketFactory.cs

@@ -11,15 +11,8 @@ public static class MqttPubAckPacketFactory
 {
     public static MqttPubAckPacket Create(MqttPublishPacket publishPacket, DispatchApplicationMessageResult dispatchApplicationMessageResult)
     {
-        if (publishPacket == null)
+        ArgumentNullException.ThrowIfNull(publishPacket);
-        {
+        ArgumentNullException.ThrowIfNull(dispatchApplicationMessageResult);
-            throw new ArgumentNullException(nameof(publishPacket));
-        }
-
-        if (dispatchApplicationMessageResult == null)
-        {
-            throw new ArgumentNullException(nameof(dispatchApplicationMessageResult));
-        }
 
         var pubAckPacket = new MqttPubAckPacket
         {

Source/MQTTnet.Server/Internal/Formatter/MqttPubCompPacketFactory.cs

@@ -11,10 +11,7 @@ public static class MqttPubCompPacketFactory
 {
     public static MqttPubCompPacket Create(MqttPubRelPacket pubRelPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
     {
-        if (pubRelPacket == null)
+        ArgumentNullException.ThrowIfNull(pubRelPacket);
-        {
-            throw new ArgumentNullException(nameof(pubRelPacket));
-        }
 
         return new MqttPubCompPacket
         {

Source/MQTTnet.Server/Internal/Formatter/MqttPubRecPacketFactory.cs

@@ -11,10 +11,7 @@ public static class MqttPubRecPacketFactory
 {
     public static MqttPacket Create(MqttPublishPacket publishPacket, DispatchApplicationMessageResult dispatchApplicationMessageResult)
     {
-        if (publishPacket == null)
+        ArgumentNullException.ThrowIfNull(publishPacket);
-        {
-            throw new ArgumentNullException(nameof(publishPacket));
-        }
 
         var pubRecPacket = new MqttPubRecPacket
         {

Source/MQTTnet.Server/Internal/Formatter/MqttPubRelPacketFactory.cs

@@ -11,10 +11,7 @@ public static class MqttPubRelPacketFactory
 {
     public static MqttPubRelPacket Create(MqttPubRecPacket pubRecPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
     {
-        if (pubRecPacket == null)
+        ArgumentNullException.ThrowIfNull(pubRecPacket);
-        {
-            throw new ArgumentNullException(nameof(pubRecPacket));
-        }
 
         return new MqttPubRelPacket
         {

Source/MQTTnet.Server/Internal/Formatter/MqttPublishPacketFactory.cs

@@ -11,10 +11,7 @@ public static class MqttPublishPacketFactory
 {
     public static MqttPublishPacket Create(MqttConnectPacket connectPacket)
     {
-        if (connectPacket == null)
+        ArgumentNullException.ThrowIfNull(connectPacket);
-        {
-            throw new ArgumentNullException(nameof(connectPacket));
-        }
 
         if (!connectPacket.WillFlag)
         {
@@ -46,10 +43,7 @@ public static class MqttPublishPacketFactory
 
     public static MqttPublishPacket Create(MqttApplicationMessage applicationMessage)
     {
-        if (applicationMessage == null)
+        ArgumentNullException.ThrowIfNull(applicationMessage);
-        {
-            throw new ArgumentNullException(nameof(applicationMessage));
-        }
 
         // Copy all values to their matching counterparts.
         // The not supported values in MQTT 3.1.1 are not serialized (excluded) later.
@@ -75,10 +69,7 @@ public static class MqttPublishPacketFactory
 
     public static MqttPublishPacket Create(MqttRetainedMessageMatch retainedMessage)
     {
-        if (retainedMessage == null)
+        ArgumentNullException.ThrowIfNull(retainedMessage);
-        {
-            throw new ArgumentNullException(nameof(retainedMessage));
-        }
 
         var publishPacket = Create(retainedMessage.ApplicationMessage);
         publishPacket.QualityOfServiceLevel = retainedMessage.SubscriptionQualityOfServiceLevel;

Source/MQTTnet.Server/Internal/Formatter/MqttSubAckPacketFactory.cs

@@ -10,15 +10,8 @@ public static class MqttSubAckPacketFactory
 {
     public static MqttSubAckPacket Create(MqttSubscribePacket subscribePacket, SubscribeResult subscribeResult)
     {
-        if (subscribePacket == null)
+        ArgumentNullException.ThrowIfNull(subscribePacket);
-        {
+        ArgumentNullException.ThrowIfNull(subscribeResult);
-            throw new ArgumentNullException(nameof(subscribePacket));
-        }
-
-        if (subscribeResult == null)
-        {
-            throw new ArgumentNullException(nameof(subscribeResult));
-        }
 
         var subAckPacket = new MqttSubAckPacket
         {

Source/MQTTnet.Server/Internal/Formatter/MqttUnsubAckPacketFactory.cs

@@ -10,15 +10,8 @@ namespace MQTTnet.Server.Internal.Formatter
     {
         public static MqttUnsubAckPacket Create(MqttUnsubscribePacket unsubscribePacket, UnsubscribeResult unsubscribeResult)
         {
-            if (unsubscribePacket == null)
+            ArgumentNullException.ThrowIfNull(unsubscribePacket);
-            {
+            ArgumentNullException.ThrowIfNull(unsubscribeResult);
-                throw new ArgumentNullException(nameof(unsubscribePacket));
-            }
-
-            if (unsubscribeResult == null)
-            {
-                throw new ArgumentNullException(nameof(unsubscribeResult));
-            }
 
             var unsubAckPacket = new MqttUnsubAckPacket
             {

Source/MQTTnet.Server/Internal/MqttClientSessionsManager.cs

@@ -38,10 +38,7 @@ public sealed class MqttClientSessionsManager : ISubscriptionChangedNotification
 
     public MqttClientSessionsManager(MqttServerOptions options, MqttRetainedMessagesManager retainedMessagesManager, MqttServerEventContainer eventContainer, IMqttNetLogger logger)
     {
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
-            throw new ArgumentNullException(nameof(logger));
-        }
 
         _logger = logger.WithSource(nameof(MqttClientSessionsManager));
         _rootLogger = logger;
@@ -53,10 +50,7 @@ public sealed class MqttClientSessionsManager : ISubscriptionChangedNotification
 
     public async Task CloseAllConnections(MqttServerClientDisconnectOptions options)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         List<MqttConnectedClient> connections;
         lock (_clients)
@@ -481,15 +475,8 @@ public sealed class MqttClientSessionsManager : ISubscriptionChangedNotification
 
     public async Task SubscribeAsync(string clientId, ICollection<MqttTopicFilter> topicFilters)
     {
-        if (clientId == null)
+        ArgumentNullException.ThrowIfNull(clientId);
-        {
+        ArgumentNullException.ThrowIfNull(topicFilters);
-            throw new ArgumentNullException(nameof(clientId));
-        }
-
-        if (topicFilters == null)
-        {
-            throw new ArgumentNullException(nameof(topicFilters));
-        }
 
         var fakeSubscribePacket = new MqttSubscribePacket();
         fakeSubscribePacket.TopicFilters.AddRange(topicFilters);
@@ -510,15 +497,8 @@ public sealed class MqttClientSessionsManager : ISubscriptionChangedNotification
 
     public Task UnsubscribeAsync(string clientId, ICollection<string> topicFilters)
     {
-        if (clientId == null)
+        ArgumentNullException.ThrowIfNull(clientId);
-        {
+        ArgumentNullException.ThrowIfNull(topicFilters);
-            throw new ArgumentNullException(nameof(clientId));
-        }
-
-        if (topicFilters == null)
-        {
-            throw new ArgumentNullException(nameof(topicFilters));
-        }
 
         var fakeUnsubscribePacket = new MqttUnsubscribePacket();
         fakeUnsubscribePacket.TopicFilters.AddRange(topicFilters);

Source/MQTTnet.Server/Internal/MqttClientStatistics.cs

@@ -50,10 +50,7 @@ namespace MQTTnet.Server.Internal
 
         public void HandleReceivedPacket(MqttPacket packet)
         {
-            if (packet == null)
+            ArgumentNullException.ThrowIfNull(packet);
-            {
-                throw new ArgumentNullException(nameof(packet));
-            }
 
             // This class is tracking all values from Clients perspective!
             LastPacketSentTimestamp = DateTime.UtcNow;
@@ -74,10 +71,7 @@ namespace MQTTnet.Server.Internal
 
         public void HandleSentPacket(MqttPacket packet)
         {
-            if (packet == null)
+            ArgumentNullException.ThrowIfNull(packet);
-            {
-                throw new ArgumentNullException(nameof(packet));
-            }
 
             // This class is tracking all values from Clients perspective!
             LastPacketReceivedTimestamp = DateTime.UtcNow;

Source/MQTTnet.Server/Internal/MqttClientSubscriptionsManager.cs

@@ -161,10 +161,7 @@ namespace MQTTnet.Server.Internal
 
         public async Task<SubscribeResult> Subscribe(MqttSubscribePacket subscribePacket, CancellationToken cancellationToken)
         {
-            if (subscribePacket == null)
+            ArgumentNullException.ThrowIfNull(subscribePacket);
-            {
-                throw new ArgumentNullException(nameof(subscribePacket));
-            }
 
             var retainedApplicationMessages = await _retainedMessagesManager.GetMessages().ConfigureAwait(false);
             var result = new SubscribeResult(subscribePacket.TopicFilters.Count);
@@ -222,10 +219,7 @@ namespace MQTTnet.Server.Internal
 
         public async Task<UnsubscribeResult> Unsubscribe(MqttUnsubscribePacket unsubscribePacket, CancellationToken cancellationToken)
         {
-            if (unsubscribePacket == null)
+            ArgumentNullException.ThrowIfNull(unsubscribePacket);
-            {
-                throw new ArgumentNullException(nameof(unsubscribePacket));
-            }
 
             var result = new UnsubscribeResult();
 

Source/MQTTnet.Server/Internal/MqttConnectedClient.cs

@@ -48,10 +48,7 @@ public sealed class MqttConnectedClient : IDisposable
         Endpoint = channelAdapter.Endpoint;
         Session = session ?? throw new ArgumentNullException(nameof(session));
 
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
-            throw new ArgumentNullException(nameof(logger));
-        }
 
         _logger = logger.WithSource(nameof(MqttConnectedClient));
     }

Source/MQTTnet.Server/Internal/MqttRetainedMessagesManager.cs

@@ -19,8 +19,7 @@ namespace MQTTnet.Server.Internal
         {
             _eventContainer = eventContainer ?? throw new ArgumentNullException(nameof(eventContainer));
 
-            if (logger == null)
+            ArgumentNullException.ThrowIfNull(logger);
-                throw new ArgumentNullException(nameof(logger));
 
             _logger = logger.WithSource(nameof(MqttRetainedMessagesManager));
         }
@@ -53,10 +52,7 @@ namespace MQTTnet.Server.Internal
 
         public async Task UpdateMessage(string clientId, MqttApplicationMessage applicationMessage)
         {
-            if (applicationMessage == null)
+            ArgumentNullException.ThrowIfNull(applicationMessage);
-            {
-                throw new ArgumentNullException(nameof(applicationMessage));
-            }
 
             try
             {

Source/MQTTnet.Server/Internal/MqttServerKeepAliveMonitor.cs

@@ -27,10 +27,7 @@ namespace MQTTnet.Server.Internal
             _options = options ?? throw new ArgumentNullException(nameof(options));
             _sessionsManager = sessionsManager ?? throw new ArgumentNullException(nameof(sessionsManager));
 
-            if (logger == null)
+            ArgumentNullException.ThrowIfNull(logger);
-            {
-                throw new ArgumentNullException(nameof(logger));
-            }
 
             _logger = logger.WithSource(nameof(MqttServerKeepAliveMonitor));
         }

Source/MQTTnet.Server/Internal/MqttSessionsStorage.cs

@@ -34,10 +34,7 @@ namespace MQTTnet.Server.Internal
 
         public bool TryGetSession(string id, out MqttSession session)
         {
-            if (id == null)
+            ArgumentNullException.ThrowIfNull(id);
-            {
-                throw new ArgumentNullException(nameof(id));
-            }
 
             if (!_sessions.TryGetValue(id, out session))
             {
@@ -63,10 +60,7 @@ namespace MQTTnet.Server.Internal
 
         public bool TryRemoveSession(string id, out MqttSession session)
         {
-            if (id == null)
+            ArgumentNullException.ThrowIfNull(id);
-            {
-                throw new ArgumentNullException(nameof(id));
-            }
 
             if (_sessions.TryGetValue(id, out session))
             {
@@ -79,10 +73,7 @@ namespace MQTTnet.Server.Internal
 
         public void UpdateSession(string id, MqttSession session)
         {
-            if (id == null)
+            ArgumentNullException.ThrowIfNull(id);
-            {
-                throw new ArgumentNullException(nameof(id));
-            }
 
             _sessions[id] = session;
         }

Source/MQTTnet.Server/MqttServer.cs

@@ -31,10 +31,7 @@ public class MqttServer : Disposable
     {
         _options = options ?? throw new ArgumentNullException(nameof(options));
 
-        if (adapters == null)
+        ArgumentNullException.ThrowIfNull(adapters);
-        {
-            throw new ArgumentNullException(nameof(adapters));
-        }
 
         _adapters = adapters.ToList();
 
@@ -202,15 +199,8 @@ public class MqttServer : Disposable
 
     public Task DisconnectClientAsync(string id, MqttServerClientDisconnectOptions options)
     {
-        if (id == null)
+        ArgumentNullException.ThrowIfNull(id);
-        {
+        ArgumentNullException.ThrowIfNull(options);
-            throw new ArgumentNullException(nameof(id));
-        }
-
-        if (options == null)
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         ThrowIfNotStarted();
 
@@ -226,10 +216,7 @@ public class MqttServer : Disposable
 
     public Task<MqttApplicationMessage> GetRetainedMessageAsync(string topic)
     {
-        if (topic == null)
+        ArgumentNullException.ThrowIfNull(topic);
-        {
-            throw new ArgumentNullException(nameof(topic));
-        }
 
         ThrowIfNotStarted();
 
@@ -252,15 +239,8 @@ public class MqttServer : Disposable
 
     public Task InjectApplicationMessage(InjectedMqttApplicationMessage injectedApplicationMessage, CancellationToken cancellationToken = default)
     {
-        if (injectedApplicationMessage == null)
+        ArgumentNullException.ThrowIfNull(injectedApplicationMessage);
-        {
+        ArgumentNullException.ThrowIfNull(injectedApplicationMessage.ApplicationMessage);
-            throw new ArgumentNullException(nameof(injectedApplicationMessage));
-        }
-
-        if (injectedApplicationMessage.ApplicationMessage == null)
-        {
-            throw new ArgumentNullException(nameof(injectedApplicationMessage.ApplicationMessage));
-        }
 
         MqttTopicValidator.ThrowIfInvalid(injectedApplicationMessage.ApplicationMessage.Topic);
 
@@ -306,10 +286,7 @@ public class MqttServer : Disposable
 
     public async Task StopAsync(MqttServerStopOptions options)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         try
         {
@@ -343,15 +320,8 @@ public class MqttServer : Disposable
 
     public Task SubscribeAsync(string clientId, ICollection<MqttTopicFilter> topicFilters)
     {
-        if (clientId == null)
+        ArgumentNullException.ThrowIfNull(clientId);
-        {
+        ArgumentNullException.ThrowIfNull(topicFilters);
-            throw new ArgumentNullException(nameof(clientId));
-        }
-
-        if (topicFilters == null)
-        {
-            throw new ArgumentNullException(nameof(topicFilters));
-        }
 
         foreach (var topicFilter in topicFilters)
         {
@@ -366,15 +336,8 @@ public class MqttServer : Disposable
 
     public Task UnsubscribeAsync(string clientId, ICollection<string> topicFilters)
     {
-        if (clientId == null)
+        ArgumentNullException.ThrowIfNull(clientId);
-        {
+        ArgumentNullException.ThrowIfNull(topicFilters);
-            throw new ArgumentNullException(nameof(clientId));
-        }
-
-        if (topicFilters == null)
-        {
-            throw new ArgumentNullException(nameof(topicFilters));
-        }
 
         ThrowIfDisposed();
         ThrowIfNotStarted();
@@ -384,10 +347,7 @@ public class MqttServer : Disposable
 
     public Task UpdateRetainedMessageAsync(MqttApplicationMessage retainedMessage)
     {
-        if (retainedMessage == null)
+        ArgumentNullException.ThrowIfNull(retainedMessage);
-        {
-            throw new ArgumentNullException(nameof(retainedMessage));
-        }
 
         ThrowIfDisposed();
         ThrowIfNotStarted();

Source/MQTTnet.Server/MqttServerExtensions.cs

@@ -13,10 +13,7 @@ public static class MqttServerExtensions
 {
     public static Task DisconnectClientAsync(this MqttServer server, string id, MqttDisconnectReasonCode reasonCode = MqttDisconnectReasonCode.NormalDisconnection)
     {
-        if (server == null)
+        ArgumentNullException.ThrowIfNull(server);
-        {
-            throw new ArgumentNullException(nameof(server));
-        }
 
         return server.DisconnectClientAsync(id, new MqttServerClientDisconnectOptions { ReasonCode = reasonCode });
     }
@@ -28,15 +25,8 @@ public static class MqttServerExtensions
         MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
         bool retain = false)
     {
-        if (server == null)
+        ArgumentNullException.ThrowIfNull(server);
-        {
+        ArgumentNullException.ThrowIfNull(topic);
-            throw new ArgumentNullException(nameof(server));
-        }
-
-        if (topic == null)
-        {
-            throw new ArgumentNullException(nameof(topic));
-        }
 
         var payloadBuffer = EmptyBuffer.Array;
         if (payload is string stringPayload)
@@ -57,50 +47,25 @@ public static class MqttServerExtensions
 
     public static Task StopAsync(this MqttServer server)
     {
-        if (server == null)
+        ArgumentNullException.ThrowIfNull(server);
-        {
-            throw new ArgumentNullException(nameof(server));
-        }
 
         return server.StopAsync(new MqttServerStopOptions());
     }
 
     public static Task SubscribeAsync(this MqttServer server, string clientId, params MqttTopicFilter[] topicFilters)
     {
-        if (server == null)
+        ArgumentNullException.ThrowIfNull(server);
-        {
+        ArgumentNullException.ThrowIfNull(clientId);
-            throw new ArgumentNullException(nameof(server));
+        ArgumentNullException.ThrowIfNull(topicFilters);
-        }
-
-        if (clientId == null)
-        {
-            throw new ArgumentNullException(nameof(clientId));
-        }
-
-        if (topicFilters == null)
-        {
-            throw new ArgumentNullException(nameof(topicFilters));
-        }
 
         return server.SubscribeAsync(clientId, topicFilters);
     }
 
     public static Task SubscribeAsync(this MqttServer server, string clientId, string topic)
     {
-        if (server == null)
+        ArgumentNullException.ThrowIfNull(server);
-        {
+        ArgumentNullException.ThrowIfNull(clientId);
-            throw new ArgumentNullException(nameof(server));
+        ArgumentNullException.ThrowIfNull(topic);
-        }
-
-        if (clientId == null)
-        {
-            throw new ArgumentNullException(nameof(clientId));
-        }
-
-        if (topic == null)
-        {
-            throw new ArgumentNullException(nameof(topic));
-        }
 
         var topicFilters = new MqttTopicFilterBuilder().WithTopic(topic).Build();
         return server.SubscribeAsync(clientId, topicFilters);

Source/MQTTnet.Server/MqttServerFactory.cs

@@ -39,10 +39,7 @@ public sealed class MqttServerFactory
 
     public MqttServer CreateMqttServer(MqttServerOptions options, IMqttNetLogger logger)
     {
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
-            throw new ArgumentNullException(nameof(logger));
-        }
 
         var serverAdapters = DefaultServerAdapters.Select(a => a.Invoke(this));
         return CreateMqttServer(options, serverAdapters, logger);
@@ -50,25 +47,15 @@ public sealed class MqttServerFactory
 
     public MqttServer CreateMqttServer(MqttServerOptions options, IEnumerable<IMqttServerAdapter> serverAdapters, IMqttNetLogger logger)
     {
-        if (serverAdapters == null)
+        ArgumentNullException.ThrowIfNull(serverAdapters);
-        {
+        ArgumentNullException.ThrowIfNull(logger);
-            throw new ArgumentNullException(nameof(serverAdapters));
-        }
-
-        if (logger == null)
-        {
-            throw new ArgumentNullException(nameof(logger));
-        }
 
         return new MqttServer(options, serverAdapters, logger);
     }
 
     public MqttServer CreateMqttServer(MqttServerOptions options, IEnumerable<IMqttServerAdapter> serverAdapters)
     {
-        if (serverAdapters == null)
+        ArgumentNullException.ThrowIfNull(serverAdapters);
-        {
-            throw new ArgumentNullException(nameof(serverAdapters));
-        }
 
         return new MqttServer(options, serverAdapters, DefaultLogger);
     }

Source/MQTTnet.Server/Options/MqttServerOptionsBuilder.cs

@@ -180,10 +180,7 @@ namespace MQTTnet.Server
 
         public MqttServerOptionsBuilder WithEncryptionCertificate(byte[] value, IMqttServerCertificateCredentials credentials = null)
         {
-            if (value == null)
+            ArgumentNullException.ThrowIfNull(value);
-            {
-                throw new ArgumentNullException(nameof(value));
-            }
 
             _options.TlsEndpointOptions.CertificateProvider = new BlobCertificateProvider(value)
             {
@@ -195,10 +192,7 @@ namespace MQTTnet.Server
 
         public MqttServerOptionsBuilder WithEncryptionCertificate(X509Certificate2 certificate)
         {
-            if (certificate == null)
+            ArgumentNullException.ThrowIfNull(certificate);
-            {
-                throw new ArgumentNullException(nameof(certificate));
-            }
 
             _options.TlsEndpointOptions.CertificateProvider = new X509CertificateProvider(certificate);
             return this;
@@ -206,10 +200,7 @@ namespace MQTTnet.Server
 
         public MqttServerOptionsBuilder WithEncryptionCertificate(ICertificateProvider certificateProvider)
         {
-            if (certificateProvider == null)
+            ArgumentNullException.ThrowIfNull(certificateProvider);
-            {
-                throw new ArgumentNullException(nameof(certificateProvider));
-            }
 
             _options.TlsEndpointOptions.CertificateProvider = certificateProvider;
 

Source/MQTTnet.Server/Status/MqttClientStatus.cs

@@ -50,10 +50,7 @@ public sealed class MqttClientStatus
 
     public Task DisconnectAsync(MqttServerClientDisconnectOptions options)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         return _client.StopAsync(options);
     }

Source/MQTTnet.Server/Status/MqttClientStatusExtensions.cs

@@ -18,10 +18,7 @@ public static class MqttClientStatusExtensions
 
     public static Task DisconnectAsync(this MqttClientStatus clientStatus)
     {
-        if (clientStatus == null)
+        ArgumentNullException.ThrowIfNull(clientStatus);
-        {
-            throw new ArgumentNullException(nameof(clientStatus));
-        }
 
         return clientStatus.DisconnectAsync(DefaultDisconnectOptions);
     }

Source/MQTTnet.Server/Status/MqttSessionStatus.cs

@@ -42,10 +42,7 @@ public sealed class MqttSessionStatus
 
     public Task DeliverApplicationMessageAsync(MqttApplicationMessage applicationMessage)
     {
-        if (applicationMessage == null)
+        ArgumentNullException.ThrowIfNull(applicationMessage);
-        {
-            throw new ArgumentNullException(nameof(applicationMessage));
-        }
 
         var packetBusItem = new MqttPacketBusItem(MqttPublishPacketFactory.Create(applicationMessage));
         _session.EnqueueDataPacket(packetBusItem);
@@ -55,10 +52,7 @@ public sealed class MqttSessionStatus
 
     public Task EnqueueApplicationMessageAsync(MqttApplicationMessage applicationMessage)
     {
-        if (applicationMessage == null)
+        ArgumentNullException.ThrowIfNull(applicationMessage);
-        {
-            throw new ArgumentNullException(nameof(applicationMessage));
-        }
 
         _session.EnqueueDataPacket(new MqttPacketBusItem(MqttPublishPacketFactory.Create(applicationMessage)));
 

Source/MQTTnet.Server/Stopping/MqttServerStopOptionsBuilder.cs

@@ -18,10 +18,7 @@ namespace MQTTnet.Server
 
         public MqttServerStopOptionsBuilder WithDefaultClientDisconnectOptions(Action<MqttServerClientDisconnectOptionsBuilder> builder)
         {
-            if (builder == null)
+            ArgumentNullException.ThrowIfNull(builder);
-            {
-                throw new ArgumentNullException(nameof(builder));
-            }
 
             var optionsBuilder = new MqttServerClientDisconnectOptionsBuilder();
             builder.Invoke(optionsBuilder);

Source/MQTTnet.TestApp/MqttNetConsoleLogger.cs

@@ -14,7 +14,7 @@ namespace MQTTnet.TestApp
 
         public static void ForwardToConsole(MqttNetEventLogger logger)
         {
-            if (logger == null) throw new ArgumentNullException(nameof(logger));
+            ArgumentNullException.ThrowIfNull(logger);
 
             logger.LogMessagePublished -= PrintToConsole;
             logger.LogMessagePublished += PrintToConsole;

Source/MQTTnet.Tests/Helpers/MqttClientExtensions.cs

@@ -11,10 +11,7 @@ namespace MQTTnet.Tests.Helpers
     {
         public static TestApplicationMessageReceivedHandler TrackReceivedMessages(this IMqttClient client)
         {
-            if (client == null)
+            ArgumentNullException.ThrowIfNull(client);
-            {
-                throw new ArgumentNullException(nameof(client));
-            }
 
             return new TestApplicationMessageReceivedHandler(client);
         }

Source/MQTTnet.Tests/Helpers/ReflectionExtensions.cs

@@ -11,10 +11,7 @@ namespace MQTTnet.Tests.Helpers
     {
         public static object GetFieldValue(this object source, string fieldName)
         {
-            if (source == null)
+            ArgumentNullException.ThrowIfNull(source);
-            {
-                throw new ArgumentNullException(nameof(source));
-            }
 
             var field = source.GetType().GetField(fieldName, BindingFlags.Instance | BindingFlags.NonPublic);
             if (field == null)

Source/MQTTnet.Tests/Mockups/TestApplicationMessageReceivedHandler.cs

@@ -18,10 +18,7 @@ namespace MQTTnet.Tests.Mockups
 
         public TestApplicationMessageReceivedHandler(IMqttClient mqttClient)
         {
-            if (mqttClient == null)
+            ArgumentNullException.ThrowIfNull(mqttClient);
-            {
-                throw new ArgumentNullException(nameof(mqttClient));
-            }
 
             mqttClient.ApplicationMessageReceivedAsync += OnApplicationMessageReceivedAsync;
         }

Source/MQTTnet.Tests/Mockups/TestEnvironment.cs

@@ -102,10 +102,7 @@ namespace MQTTnet.Tests.Mockups
 
         public async Task<IMqttClient> ConnectClient(Action<MqttClientOptionsBuilder> configureOptions, TimeSpan timeout = default)
         {
-            if (configureOptions == null)
+            ArgumentNullException.ThrowIfNull(configureOptions);
-            {
-                throw new ArgumentNullException(nameof(configureOptions));
-            }
 
             // Start with initial default values.
             var optionsBuilder = ClientFactory.CreateClientOptionsBuilder().WithProtocolVersion(_protocolVersion).WithTcpServer("127.0.0.1", ServerPort);
@@ -134,10 +131,7 @@ namespace MQTTnet.Tests.Mockups
 
         public async Task<IMqttClient> ConnectClient(MqttClientOptionsBuilder options, TimeSpan timeout = default)
         {
-            if (options == null)
+            ArgumentNullException.ThrowIfNull(options);
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
 
             options = options.WithTcpServer("127.0.0.1", ServerPort);
 
@@ -160,10 +154,7 @@ namespace MQTTnet.Tests.Mockups
 
         public async Task<IMqttClient> ConnectClient(MqttClientOptions options, TimeSpan timeout = default)
         {
-            if (options == null)
+            ArgumentNullException.ThrowIfNull(options);
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
 
             var client = CreateClient();
 

Source/MQTTnet/Adapter/MqttChannelAdapter.cs

@@ -38,10 +38,7 @@ public sealed class MqttChannelAdapter : Disposable, IMqttChannelAdapter
 
         PacketFormatterAdapter = packetFormatterAdapter ?? throw new ArgumentNullException(nameof(packetFormatterAdapter));
 
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
-            throw new ArgumentNullException(nameof(logger));
-        }
 
         _logger = logger.WithSource(nameof(MqttChannelAdapter));
     }

Source/MQTTnet/Adapter/MqttPacketInspector.cs

@@ -23,10 +23,7 @@ public sealed class MqttPacketInspector
     {
         _asyncEvent = asyncEvent ?? throw new ArgumentNullException(nameof(asyncEvent));
 
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
-            throw new ArgumentNullException(nameof(logger));
-        }
 
         _logger = logger.WithSource(nameof(MqttPacketInspector));
     }

Source/MQTTnet/Connecting/MqttClientConnectResultFactory.cs

@@ -14,10 +14,7 @@ public sealed class MqttClientConnectResultFactory
 {
     public MqttClientConnectResult Create(MqttConnAckPacket connAckPacket, MqttProtocolVersion protocolVersion)
     {
-        if (connAckPacket == null)
+        ArgumentNullException.ThrowIfNull(connAckPacket);
-        {
-            throw new ArgumentNullException(nameof(connAckPacket));
-        }
 
         if (protocolVersion == MqttProtocolVersion.V500)
         {
@@ -68,10 +65,8 @@ public sealed class MqttClientConnectResultFactory
 
     static MqttClientConnectResult CreateForMqtt311(MqttConnAckPacket connAckPacket)
     {
-        if (connAckPacket == null)
+        ArgumentNullException.ThrowIfNull(connAckPacket);
-        {
+
-            throw new ArgumentNullException(nameof(connAckPacket));
-        }
 
         return new MqttClientConnectResult
         {
@@ -84,10 +79,7 @@ public sealed class MqttClientConnectResultFactory
 
     static MqttClientConnectResult CreateForMqtt500(MqttConnAckPacket connAckPacket)
     {
-        if (connAckPacket == null)
+        ArgumentNullException.ThrowIfNull(connAckPacket);
-        {
-            throw new ArgumentNullException(nameof(connAckPacket));
-        }
 
         return new MqttClientConnectResult
         {

Source/MQTTnet/Diagnostics/Logger/MqttNetSourceLoggerExtensions.cs

@@ -209,10 +209,7 @@ namespace MQTTnet.Diagnostics.Logger
 
         public static MqttNetSourceLogger WithSource(this IMqttNetLogger logger, string source)
         {
-            if (logger == null)
+            ArgumentNullException.ThrowIfNull(logger);
-            {
-                throw new ArgumentNullException(nameof(logger));
-            }
 
             return new MqttNetSourceLogger(logger, source);
         }

Source/MQTTnet/Disconnecting/MqttClientDisconnectOptionsValidator.cs

@@ -12,10 +12,7 @@ public static class MqttClientDisconnectOptionsValidator
 {
     public static void ThrowIfNotSupported(MqttClientDisconnectOptions options, MqttProtocolVersion protocolVersion)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         if (protocolVersion == MqttProtocolVersion.V500)
         {

Source/MQTTnet/ExtendedAuthenticationExchange/MqttExtendedAuthenticationExchangeContext.cs

@@ -13,10 +13,7 @@ public class MqttExtendedAuthenticationExchangeContext
 {
     public MqttExtendedAuthenticationExchangeContext(MqttAuthPacket authPacket, MqttClient client)
     {
-        if (authPacket == null)
+        ArgumentNullException.ThrowIfNull(authPacket);
-        {
-            throw new ArgumentNullException(nameof(authPacket));
-        }
 
         ReasonCode = authPacket.ReasonCode;
         ReasonString = authPacket.ReasonString;

Source/MQTTnet/Formatter/MqttApplicationMessageFactory.cs

@@ -11,10 +11,7 @@ namespace MQTTnet.Formatter
     {
         public static MqttApplicationMessage Create(MqttPublishPacket publishPacket)
         {
-            if (publishPacket == null)
+            ArgumentNullException.ThrowIfNull(publishPacket);
-            {
-                throw new ArgumentNullException(nameof(publishPacket));
-            }
 
             return new MqttApplicationMessage
             {

Source/MQTTnet/Formatter/MqttBufferWriter.cs

@@ -105,10 +105,7 @@ namespace MQTTnet.Formatter
 
         public void Write(MqttBufferWriter propertyWriter)
         {
-            if (propertyWriter == null)
+            ArgumentNullException.ThrowIfNull(propertyWriter);
-            {
-                throw new ArgumentNullException(nameof(propertyWriter));
-            }
 
             WriteBinary(propertyWriter._buffer, 0, propertyWriter.Length);
         }
@@ -140,10 +137,7 @@ namespace MQTTnet.Formatter
 
         public void WriteBinary(byte[] buffer, int offset, int count)
         {
-            if (buffer == null)
+            ArgumentNullException.ThrowIfNull(buffer);
-            {
-                throw new ArgumentNullException(nameof(buffer));
-            }
 
             if (count == 0)
             {

Source/MQTTnet/Formatter/MqttConnectPacketFactory.cs

@@ -11,10 +11,7 @@ public static class MqttConnectPacketFactory
 {
     public static MqttConnectPacket Create(MqttClientOptions clientOptions)
     {
-        if (clientOptions == null)
+        ArgumentNullException.ThrowIfNull(clientOptions);
-        {
-            throw new ArgumentNullException(nameof(clientOptions));
-        }
 
         var connectPacket = new MqttConnectPacket
         {

Source/MQTTnet/Formatter/MqttPubAckPacketFactory.cs

@@ -12,10 +12,7 @@ public static class MqttPubAckPacketFactory
 {
     public static MqttPubAckPacket Create(MqttApplicationMessageReceivedEventArgs applicationMessageReceivedEventArgs)
     {
-        if (applicationMessageReceivedEventArgs == null)
+        ArgumentNullException.ThrowIfNull(applicationMessageReceivedEventArgs);
-        {
-            throw new ArgumentNullException(nameof(applicationMessageReceivedEventArgs));
-        }
 
         var pubAckPacket = new MqttPubAckPacket
         {

Source/MQTTnet/Formatter/MqttPubCompPacketFactory.cs

@@ -12,10 +12,7 @@ public static class MqttPubCompPacketFactory
 {
     public static MqttPubCompPacket Create(MqttPubRelPacket pubRelPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
     {
-        if (pubRelPacket == null)
+        ArgumentNullException.ThrowIfNull(pubRelPacket);
-        {
-            throw new ArgumentNullException(nameof(pubRelPacket));
-        }
 
         return new MqttPubCompPacket
         {

Source/MQTTnet/Formatter/MqttPubRecPacketFactory.cs

@@ -12,10 +12,7 @@ public static class MqttPubRecPacketFactory
 {
     public static MqttPubRecPacket Create(MqttApplicationMessageReceivedEventArgs applicationMessageReceivedEventArgs)
     {
-        if (applicationMessageReceivedEventArgs == null)
+        ArgumentNullException.ThrowIfNull(applicationMessageReceivedEventArgs);
-        {
-            throw new ArgumentNullException(nameof(applicationMessageReceivedEventArgs));
-        }
 
         var pubRecPacket = Create(applicationMessageReceivedEventArgs.PublishPacket, applicationMessageReceivedEventArgs.ReasonCode);
         pubRecPacket.UserProperties = applicationMessageReceivedEventArgs.ResponseUserProperties;

Source/MQTTnet/Formatter/MqttPubRelPacketFactory.cs

@@ -12,10 +12,7 @@ public static class MqttPubRelPacketFactory
 {
     public static MqttPubRelPacket Create(MqttPubRecPacket pubRecPacket, MqttApplicationMessageReceivedReasonCode reasonCode)
     {
-        if (pubRecPacket == null)
+        ArgumentNullException.ThrowIfNull(pubRecPacket);
-        {
-            throw new ArgumentNullException(nameof(pubRecPacket));
-        }
 
         return new MqttPubRelPacket
         {

Source/MQTTnet/Formatter/MqttPublishPacketFactory.cs

@@ -12,10 +12,7 @@ namespace MQTTnet.Formatter
     {
         public static MqttPublishPacket Create(MqttApplicationMessage applicationMessage)
         {
-            if (applicationMessage == null)
+            ArgumentNullException.ThrowIfNull(applicationMessage);
-            {
-                throw new ArgumentNullException(nameof(applicationMessage));
-            }
 
             // Copy all values to their matching counterparts.
             // The not supported values in MQTT 3.1.1 are not serialized (excluded) later.

Source/MQTTnet/Formatter/MqttSubscribePacketFactory.cs

@@ -11,10 +11,7 @@ public static class MqttSubscribePacketFactory
 {
     public static MqttSubscribePacket Create(MqttClientSubscribeOptions clientSubscribeOptions)
     {
-        if (clientSubscribeOptions == null)
+        ArgumentNullException.ThrowIfNull(clientSubscribeOptions);
-        {
-            throw new ArgumentNullException(nameof(clientSubscribeOptions));
-        }
 
         var packet = new MqttSubscribePacket
         {

Source/MQTTnet/Formatter/MqttUnsubscribePacketFactory.cs

@@ -11,10 +11,7 @@ public static class MqttUnsubscribePacketFactory
 {
     public static MqttUnsubscribePacket Create(MqttClientUnsubscribeOptions clientUnsubscribeOptions)
     {
-        if (clientUnsubscribeOptions == null)
+        ArgumentNullException.ThrowIfNull(clientUnsubscribeOptions);
-        {
-            throw new ArgumentNullException(nameof(clientUnsubscribeOptions));
-        }
 
         var packet = new MqttUnsubscribePacket
         {

Source/MQTTnet/Formatter/V3/MqttV3PacketFormatter.cs

@@ -91,10 +91,7 @@ namespace MQTTnet.Formatter.V3
 
         public MqttPacketBuffer Encode(MqttPacket packet)
         {
-            if (packet == null)
+            ArgumentNullException.ThrowIfNull(packet);
-            {
-                throw new ArgumentNullException(nameof(packet));
-            }
 
             // Leave enough head space for max header size (fixed + 4 variable remaining length = 5 bytes)
             _bufferWriter.Reset(5);
@@ -797,10 +794,7 @@ namespace MQTTnet.Formatter.V3
 
         void ValidateConnectPacket(MqttConnectPacket packet)
         {
-            if (packet == null)
+            ArgumentNullException.ThrowIfNull(packet);
-            {
-                throw new ArgumentNullException(nameof(packet));
-            }
 
             if (string.IsNullOrEmpty(packet.ClientId) && !packet.CleanSession)
             {

Source/MQTTnet/Formatter/V5/MqttV5PacketEncoder.cs

@@ -25,10 +25,7 @@ public sealed class MqttV5PacketEncoder
 
     public MqttPacketBuffer Encode(MqttPacket packet)
     {
-        if (packet == null)
+        ArgumentNullException.ThrowIfNull(packet);
-        {
-            throw new ArgumentNullException(nameof(packet));
-        }
 
         // Leave enough head space for max header size (fixed + 4 variable remaining length = 5 bytes)
         const int ReservedHeaderSize = 5;

Source/MQTTnet/Formatter/V5/MqttV5PropertiesWriter.cs

@@ -230,10 +230,7 @@ namespace MQTTnet.Formatter.V5
 
         public void WriteTo(MqttBufferWriter target)
         {
-            if (target == null)
+            ArgumentNullException.ThrowIfNull(target);
-            {
-                throw new ArgumentNullException(nameof(target));
-            }
 
             target.WriteVariableByteInteger((uint)_bufferWriter.Length);
             target.Write(_bufferWriter);

Source/MQTTnet/Implementations/CrossPlatformSocket.cs

@@ -124,20 +124,14 @@ public sealed class CrossPlatformSocket : IDisposable
 
     public void Bind(EndPoint localEndPoint)
     {
-        if (localEndPoint is null)
+        ArgumentNullException.ThrowIfNull(localEndPoint);
-        {
-            throw new ArgumentNullException(nameof(localEndPoint));
-        }
 
         _socket.Bind(localEndPoint);
     }
 
     public async Task ConnectAsync(EndPoint endPoint, CancellationToken cancellationToken)
     {
-        if (endPoint is null)
+        ArgumentNullException.ThrowIfNull(endPoint);
-        {
-            throw new ArgumentNullException(nameof(endPoint));
-        }
 
         cancellationToken.ThrowIfCancellationRequested();
 

Source/MQTTnet/Implementations/MqttClientAdapterFactory.cs

@@ -14,7 +14,7 @@ namespace MQTTnet.Implementations
     {
         public IMqttChannelAdapter CreateClientAdapter(MqttClientOptions options, MqttPacketInspector packetInspector, IMqttNetLogger logger)
         {
-            if (options == null) throw new ArgumentNullException(nameof(options));
+            ArgumentNullException.ThrowIfNull(options);
 
             IMqttChannel channel;
             switch (options.ChannelOptions)

Source/MQTTnet/Internal/AsyncEvent.cs

@@ -26,10 +26,7 @@ namespace MQTTnet.Internal
 
         public void AddHandler(Func<TEventArgs, Task> handler)
         {
-            if (handler == null)
+            ArgumentNullException.ThrowIfNull(handler);
-            {
-                throw new ArgumentNullException(nameof(handler));
-            }
 
             lock (_handlers)
             {
@@ -42,10 +39,7 @@ namespace MQTTnet.Internal
 
         public void AddHandler(Action<TEventArgs> handler)
         {
-            if (handler == null)
+            ArgumentNullException.ThrowIfNull(handler);
-            {
-                throw new ArgumentNullException(nameof(handler));
-            }
 
             lock (_handlers)
             {
@@ -75,10 +69,7 @@ namespace MQTTnet.Internal
 
         public void RemoveHandler(Func<TEventArgs, Task> handler)
         {
-            if (handler == null)
+            ArgumentNullException.ThrowIfNull(handler);
-            {
-                throw new ArgumentNullException(nameof(handler));
-            }
 
             lock (_handlers)
             {
@@ -91,10 +82,7 @@ namespace MQTTnet.Internal
 
         public void RemoveHandler(Action<TEventArgs> handler)
         {
-            if (handler == null)
+            ArgumentNullException.ThrowIfNull(handler);
-            {
-                throw new ArgumentNullException(nameof(handler));
-            }
 
             lock (_handlers)
             {
@@ -107,15 +95,8 @@ namespace MQTTnet.Internal
 
         public async Task TryInvokeAsync(TEventArgs eventArgs, MqttNetSourceLogger logger)
         {
-            if (eventArgs == null)
+            ArgumentNullException.ThrowIfNull(eventArgs);
-            {
+            ArgumentNullException.ThrowIfNull(logger);
-                throw new ArgumentNullException(nameof(eventArgs));
-            }
-
-            if (logger == null)
-            {
-                throw new ArgumentNullException(nameof(logger));
-            }
 
             try
             {

Source/MQTTnet/Internal/AsyncLock.cs

@@ -116,10 +116,7 @@ namespace MQTTnet.Internal
 
             public bool Approve(IDisposable scope)
             {
-                if (scope == null)
+                ArgumentNullException.ThrowIfNull(scope);
-                {
-                    throw new ArgumentNullException(nameof(scope));
-                }
 
                 if (_promise.Task.IsCompleted)
                 {

Source/MQTTnet/Internal/BlockingQueue.cs

@@ -28,7 +28,7 @@ namespace MQTTnet.Internal
 
         public void Enqueue(TItem item)
         {
-            if (item == null) throw new ArgumentNullException(nameof(item));
+            ArgumentNullException.ThrowIfNull(item);
 
             lock (_syncRoot)
             {
@@ -88,7 +88,7 @@ namespace MQTTnet.Internal
 
         public void RemoveFirst(Predicate<TItem> match)
         {
-            if (match == null) throw new ArgumentNullException(nameof(match));
+            ArgumentNullException.ThrowIfNull(match);
 
             lock (_syncRoot)
             {

Source/MQTTnet/Internal/MqttPacketBus.cs

@@ -124,10 +124,7 @@ namespace MQTTnet.Internal
 
         public void EnqueueItem(MqttPacketBusItem item, MqttPacketBusPartition partition)
         {
-            if (item == null)
+            ArgumentNullException.ThrowIfNull(item);
-            {
-                throw new ArgumentNullException(nameof(item));
-            }
 
             lock (_syncRoot)
             {

Source/MQTTnet/Internal/TaskExtensions.cs

@@ -24,10 +24,7 @@ namespace MQTTnet.Internal
 
         public static async Task WaitAsync(this Task task, Task sender, MqttNetSourceLogger logger)
         {
-            if (logger == null)
+            ArgumentNullException.ThrowIfNull(logger);
-            {
-                throw new ArgumentNullException(nameof(logger));
-            }
 
             if (task == null)
             {

Source/MQTTnet/LowLevelClient/LowLevelMqttClient.cs

@@ -41,10 +41,7 @@ namespace MQTTnet.LowLevelClient
 
         public async Task ConnectAsync(MqttClientOptions options, CancellationToken cancellationToken)
         {
-            if (options is null)
+            ArgumentNullException.ThrowIfNull(options);
-            {
-                throw new ArgumentNullException(nameof(options));
-            }
 
             if (_adapter != null)
             {
@@ -127,10 +124,7 @@ namespace MQTTnet.LowLevelClient
 
         public async Task SendAsync(MqttPacket packet, CancellationToken cancellationToken)
         {
-            if (packet is null)
+            ArgumentNullException.ThrowIfNull(packet);
-            {
-                throw new ArgumentNullException(nameof(packet));
-            }
 
             var adapter = _adapter;
             if (adapter == null)

Source/MQTTnet/MqttApplicationMessageExtensions.cs

@@ -11,10 +11,7 @@ public static class MqttApplicationMessageExtensions
 {
     public static string ConvertPayloadToString(this MqttApplicationMessage applicationMessage)
     {
-        if (applicationMessage == null)
+        ArgumentNullException.ThrowIfNull(applicationMessage);
-        {
-            throw new ArgumentNullException(nameof(applicationMessage));
-        }
 
         if (applicationMessage.Payload.Length == 0)
         {

Source/MQTTnet/MqttApplicationMessageValidator.cs

@@ -13,10 +13,7 @@ namespace MQTTnet
     {
         public static void ThrowIfNotSupported(MqttApplicationMessage applicationMessage, MqttProtocolVersion protocolVersion)
         {
-            if (applicationMessage == null)
+            ArgumentNullException.ThrowIfNull(applicationMessage);
-            {
-                throw new ArgumentNullException(nameof(applicationMessage));
-            }
 
             if (protocolVersion == MqttProtocolVersion.V500)
             {

Source/MQTTnet/MqttClient.cs

@@ -183,10 +183,7 @@ public sealed class MqttClient : Disposable, IMqttClient
 
     public async Task DisconnectAsync(MqttClientDisconnectOptions options, CancellationToken cancellationToken = default)
     {
-        if (options is null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         ThrowIfDisposed();
 
@@ -293,10 +290,7 @@ public sealed class MqttClient : Disposable, IMqttClient
 
     public Task SendExtendedAuthenticationExchangeDataAsync(MqttExtendedAuthenticationExchangeData data, CancellationToken cancellationToken = default)
     {
-        if (data == null)
+        ArgumentNullException.ThrowIfNull(data);
-        {
-            throw new ArgumentNullException(nameof(data));
-        }
 
         ThrowIfDisposed();
         ThrowIfNotConnected();
@@ -316,10 +310,7 @@ public sealed class MqttClient : Disposable, IMqttClient
 
     public async Task<MqttClientSubscribeResult> SubscribeAsync(MqttClientSubscribeOptions options, CancellationToken cancellationToken = default)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         foreach (var topicFilter in options.TopicFilters)
         {
@@ -355,10 +346,7 @@ public sealed class MqttClient : Disposable, IMqttClient
 
     public async Task<MqttClientUnsubscribeResult> UnsubscribeAsync(MqttClientUnsubscribeOptions options, CancellationToken cancellationToken = default)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         foreach (var topicFilter in options.TopicFilters)
         {
@@ -919,10 +907,7 @@ public sealed class MqttClient : Disposable, IMqttClient
 
     static void ThrowIfOptionsInvalid(MqttClientOptions options)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         if (options.ChannelOptions == null)
         {

Source/MQTTnet/MqttClientExtensions.cs

@@ -23,10 +23,7 @@ public static class MqttClientExtensions
         List<MqttUserProperty> userProperties = null,
         CancellationToken cancellationToken = default)
     {
-        if (client == null)
+        ArgumentNullException.ThrowIfNull(client);
-        {
-            throw new ArgumentNullException(nameof(client));
-        }
 
         var disconnectOptions = new MqttClientDisconnectOptions
         {
@@ -47,15 +44,8 @@ public static class MqttClientExtensions
         bool retain = false,
         CancellationToken cancellationToken = default)
     {
-        if (mqttClient == null)
+        ArgumentNullException.ThrowIfNull(mqttClient);
-        {
+        ArgumentNullException.ThrowIfNull(topic);
-            throw new ArgumentNullException(nameof(mqttClient));
-        }
-
-        if (topic == null)
-        {
-            throw new ArgumentNullException(nameof(topic));
-        }
 
         var applicationMessage = new MqttApplicationMessageBuilder().WithTopic(topic)
             .WithPayload(payload)
@@ -74,15 +64,8 @@ public static class MqttClientExtensions
         bool retain = false,
         CancellationToken cancellationToken = default)
     {
-        if (mqttClient == null)
+        ArgumentNullException.ThrowIfNull(mqttClient);
-        {
+        ArgumentNullException.ThrowIfNull(topic);
-            throw new ArgumentNullException(nameof(mqttClient));
-        }
-
-        if (topic == null)
-        {
-            throw new ArgumentNullException(nameof(topic));
-        }
 
         var applicationMessage = new MqttApplicationMessageBuilder().WithTopic(topic)
             .WithPayload(payload)
@@ -118,25 +101,15 @@ public static class MqttClientExtensions
 
     public static Task SendExtendedAuthenticationExchangeDataAsync(this IMqttClient client, MqttExtendedAuthenticationExchangeData data)
     {
-        if (client == null)
+        ArgumentNullException.ThrowIfNull(client);
-        {
-            throw new ArgumentNullException(nameof(client));
-        }
 
         return client.SendExtendedAuthenticationExchangeDataAsync(data, CancellationToken.None);
     }
 
     public static Task<MqttClientSubscribeResult> SubscribeAsync(this IMqttClient mqttClient, MqttTopicFilter topicFilter, CancellationToken cancellationToken = default)
     {
-        if (mqttClient == null)
+        ArgumentNullException.ThrowIfNull(mqttClient);
-        {
+        ArgumentNullException.ThrowIfNull(topicFilter);
-            throw new ArgumentNullException(nameof(mqttClient));
-        }
-
-        if (topicFilter == null)
-        {
-            throw new ArgumentNullException(nameof(topicFilter));
-        }
 
         var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(topicFilter).Build();
 
@@ -149,15 +122,8 @@ public static class MqttClientExtensions
         MqttQualityOfServiceLevel qualityOfServiceLevel = MqttQualityOfServiceLevel.AtMostOnce,
         CancellationToken cancellationToken = default)
     {
-        if (mqttClient == null)
+        ArgumentNullException.ThrowIfNull(mqttClient);
-        {
+        ArgumentNullException.ThrowIfNull(topic);
-            throw new ArgumentNullException(nameof(mqttClient));
-        }
-
-        if (topic == null)
-        {
-            throw new ArgumentNullException(nameof(topic));
-        }
 
         var subscribeOptions = new MqttClientSubscribeOptionsBuilder().WithTopicFilter(topic, qualityOfServiceLevel).Build();
 
@@ -169,10 +135,7 @@ public static class MqttClientExtensions
         MqttClientDisconnectOptionsReason reason = MqttClientDisconnectOptionsReason.NormalDisconnection,
         string reasonString = null)
     {
-        if (client == null)
+        ArgumentNullException.ThrowIfNull(client);
-        {
-            throw new ArgumentNullException(nameof(client));
-        }
 
         try
         {
@@ -189,10 +152,7 @@ public static class MqttClientExtensions
 
     public static async Task<bool> TryPingAsync(this IMqttClient client, CancellationToken cancellationToken = default)
     {
-        if (client == null)
+        ArgumentNullException.ThrowIfNull(client);
-        {
-            throw new ArgumentNullException(nameof(client));
-        }
 
         try
         {
@@ -209,15 +169,8 @@ public static class MqttClientExtensions
 
     public static Task<MqttClientUnsubscribeResult> UnsubscribeAsync(this IMqttClient mqttClient, string topic, CancellationToken cancellationToken = default)
     {
-        if (mqttClient == null)
+        ArgumentNullException.ThrowIfNull(mqttClient);
-        {
+        ArgumentNullException.ThrowIfNull(topic);
-            throw new ArgumentNullException(nameof(mqttClient));
-        }
-
-        if (topic == null)
-        {
-            throw new ArgumentNullException(nameof(topic));
-        }
 
         var unsubscribeOptions = new MqttClientUnsubscribeOptionsBuilder().WithTopicFilter(topic).Build();
 

Source/MQTTnet/MqttClientFactory.cs

@@ -52,35 +52,22 @@ public sealed class MqttClientFactory
 
     public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger)
     {
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
-            throw new ArgumentNullException(nameof(logger));
-        }
 
         return new LowLevelMqttClient(_clientAdapterFactory, logger);
     }
 
     public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttClientAdapterFactory clientAdapterFactory)
     {
-        if (clientAdapterFactory == null)
+        ArgumentNullException.ThrowIfNull(clientAdapterFactory);
-        {
-            throw new ArgumentNullException(nameof(clientAdapterFactory));
-        }
 
         return new LowLevelMqttClient(_clientAdapterFactory, DefaultLogger);
     }
 
     public ILowLevelMqttClient CreateLowLevelMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory clientAdapterFactory)
     {
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
+        ArgumentNullException.ThrowIfNull(clientAdapterFactory);
-            throw new ArgumentNullException(nameof(logger));
-        }
-
-        if (clientAdapterFactory == null)
-        {
-            throw new ArgumentNullException(nameof(clientAdapterFactory));
-        }
 
         return new LowLevelMqttClient(_clientAdapterFactory, logger);
     }
@@ -92,35 +79,22 @@ public sealed class MqttClientFactory
 
     public IMqttClient CreateMqttClient(IMqttNetLogger logger)
     {
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
-            throw new ArgumentNullException(nameof(logger));
-        }
 
         return new MqttClient(_clientAdapterFactory, logger);
     }
 
     public IMqttClient CreateMqttClient(IMqttClientAdapterFactory clientAdapterFactory)
     {
-        if (clientAdapterFactory == null)
+        ArgumentNullException.ThrowIfNull(clientAdapterFactory);
-        {
-            throw new ArgumentNullException(nameof(clientAdapterFactory));
-        }
 
         return new MqttClient(clientAdapterFactory, DefaultLogger);
     }
 
     public IMqttClient CreateMqttClient(IMqttNetLogger logger, IMqttClientAdapterFactory clientAdapterFactory)
     {
-        if (logger == null)
+        ArgumentNullException.ThrowIfNull(logger);
-        {
+        ArgumentNullException.ThrowIfNull(clientAdapterFactory);
-            throw new ArgumentNullException(nameof(logger));
-        }
-
-        if (clientAdapterFactory == null)
-        {
-            throw new ArgumentNullException(nameof(clientAdapterFactory));
-        }
 
         return new MqttClient(clientAdapterFactory, logger);
     }

Source/MQTTnet/Options/MqttClientOptionsBuilder.cs

@@ -131,10 +131,7 @@ public sealed class MqttClientOptionsBuilder
 
     public MqttClientOptionsBuilder WithConnectionUri(Uri uri)
     {
-        if (uri == null)
+        ArgumentNullException.ThrowIfNull(uri);
-        {
-            throw new ArgumentNullException(nameof(uri));
-        }
 
         var port = uri.IsDefaultPort ? null : (int?)uri.Port;
         switch (uri.Scheme.ToLower())
@@ -286,10 +283,7 @@ public sealed class MqttClientOptionsBuilder
 
     public MqttClientOptionsBuilder WithTcpServer(string host, int? port = null, AddressFamily addressFamily = AddressFamily.Unspecified)
     {
-        if (host == null)
+        ArgumentNullException.ThrowIfNull(host);
-        {
-            throw new ArgumentNullException(nameof(host));
-        }
 
         _tcpOptions = new MqttClientTcpOptions();
 
@@ -303,10 +297,7 @@ public sealed class MqttClientOptionsBuilder
 
     public MqttClientOptionsBuilder WithTcpServer(Action<MqttClientTcpOptions> optionsBuilder)
     {
-        if (optionsBuilder == null)
+        ArgumentNullException.ThrowIfNull(optionsBuilder);
-        {
-            throw new ArgumentNullException(nameof(optionsBuilder));
-        }
 
         _tcpOptions = new MqttClientTcpOptions();
         optionsBuilder.Invoke(_tcpOptions);
@@ -332,10 +323,7 @@ public sealed class MqttClientOptionsBuilder
 
     public MqttClientOptionsBuilder WithTlsOptions(Action<MqttClientTlsOptionsBuilder> configure)
     {
-        if (configure == null)
+        ArgumentNullException.ThrowIfNull(configure);
-        {
-            throw new ArgumentNullException(nameof(configure));
-        }
 
         var builder = new MqttClientTlsOptionsBuilder();
         configure.Invoke(builder);
@@ -377,10 +365,7 @@ public sealed class MqttClientOptionsBuilder
 
     public MqttClientOptionsBuilder WithWebSocketServer(Action<MqttClientWebSocketOptionsBuilder> configure)
     {
-        if (configure == null)
+        ArgumentNullException.ThrowIfNull(configure);
-        {
-            throw new ArgumentNullException(nameof(configure));
-        }
 
         var webSocketOptionsBuilder = new MqttClientWebSocketOptionsBuilder();
         configure.Invoke(webSocketOptionsBuilder);

Source/MQTTnet/Options/MqttClientOptionsValidator.cs

@@ -13,10 +13,7 @@ public static class MqttClientOptionsValidator
 {
     public static void ThrowIfNotSupported(MqttClientOptions options)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         if (options.ProtocolVersion == MqttProtocolVersion.V500)
         {

Source/MQTTnet/Options/MqttClientTlsOptionsBuilder.cs

@@ -38,10 +38,7 @@ public sealed class MqttClientTlsOptionsBuilder
 
     public MqttClientTlsOptionsBuilder WithCertificateValidationHandler(Func<MqttClientCertificateValidationEventArgs, bool> certificateValidationHandler)
     {
-        if (certificateValidationHandler == null)
+        ArgumentNullException.ThrowIfNull(certificateValidationHandler);
-        {
-            throw new ArgumentNullException(nameof(certificateValidationHandler));
-        }
 
         _tlsOptions.CertificateValidationHandler = certificateValidationHandler;
         return this;
@@ -49,10 +46,7 @@ public sealed class MqttClientTlsOptionsBuilder
 
     public MqttClientTlsOptionsBuilder WithCertificateSelectionHandler(Func<MqttClientCertificateSelectionEventArgs, X509Certificate> certificateSelectionHandler)
     {
-        if (certificateSelectionHandler == null)
+        ArgumentNullException.ThrowIfNull(certificateSelectionHandler);
-        {
-            throw new ArgumentNullException(nameof(certificateSelectionHandler));
-        }
 
         _tlsOptions.CertificateSelectionHandler = certificateSelectionHandler;
         return this;
@@ -60,10 +54,7 @@ public sealed class MqttClientTlsOptionsBuilder
 
     public MqttClientTlsOptionsBuilder WithClientCertificates(IEnumerable<X509Certificate2> certificates)
     {
-        if (certificates == null)
+        ArgumentNullException.ThrowIfNull(certificates);
-        {
-            throw new ArgumentNullException(nameof(certificates));
-        }
 
         _tlsOptions.ClientCertificatesProvider = new DefaultMqttCertificatesProvider(certificates);
         return this;
@@ -71,10 +62,7 @@ public sealed class MqttClientTlsOptionsBuilder
 
     public MqttClientTlsOptionsBuilder WithClientCertificates(X509Certificate2Collection certificates)
     {
-        if (certificates == null)
+        ArgumentNullException.ThrowIfNull(certificates);
-        {
-            throw new ArgumentNullException(nameof(certificates));
-        }
 
         _tlsOptions.ClientCertificatesProvider = new DefaultMqttCertificatesProvider(certificates);
         return this;

Source/MQTTnet/Options/MqttClientWebSocketOptionsBuilder.cs

@@ -43,10 +43,7 @@ public sealed class MqttClientWebSocketOptionsBuilder
 
     public MqttClientWebSocketOptionsBuilder WithProxyOptions(Action<MqttClientWebSocketProxyOptionsBuilder> configure)
     {
-        if (configure == null)
+        ArgumentNullException.ThrowIfNull(configure);
-        {
-            throw new ArgumentNullException(nameof(configure));
-        }
 
         var proxyOptionsBuilder = new MqttClientWebSocketProxyOptionsBuilder();
         configure.Invoke(proxyOptionsBuilder);

Source/MQTTnet/PacketDispatcher/MqttPacketDispatcher.cs

@@ -46,10 +46,7 @@ namespace MQTTnet.PacketDispatcher
 
         public void Dispose(Exception exception)
         {
-            if (exception == null)
+            ArgumentNullException.ThrowIfNull(exception);
-            {
-                throw new ArgumentNullException(nameof(exception));
-            }
 
             lock (_waiters)
             {
@@ -63,10 +60,7 @@ namespace MQTTnet.PacketDispatcher
 
         public void FailAll(Exception exception)
         {
-            if (exception == null)
+            ArgumentNullException.ThrowIfNull(exception);
-            {
-                throw new ArgumentNullException(nameof(exception));
-            }
 
             lock (_waiters)
             {
@@ -81,10 +75,7 @@ namespace MQTTnet.PacketDispatcher
 
         public void RemoveAwaitable(IMqttPacketAwaitable awaitable)
         {
-            if (awaitable == null)
+            ArgumentNullException.ThrowIfNull(awaitable);
-            {
-                throw new ArgumentNullException(nameof(awaitable));
-            }
 
             lock (_waiters)
             {
@@ -94,10 +85,7 @@ namespace MQTTnet.PacketDispatcher
 
         public bool TryDispatch(MqttPacket packet)
         {
-            if (packet == null)
+            ArgumentNullException.ThrowIfNull(packet);
-            {
-                throw new ArgumentNullException(nameof(packet));
-            }
 
             ushort identifier = 0;
             if (packet is MqttPacketWithIdentifier packetWithIdentifier)

Source/MQTTnet/Packets/MqttPacketExtensions.cs

@@ -10,10 +10,7 @@ public static class MqttPacketExtensions
 {
     public static string GetRfcName(this MqttPacket packet)
     {
-        if (packet == null)
+        ArgumentNullException.ThrowIfNull(packet);
-        {
-            throw new ArgumentNullException(nameof(packet));
-        }
 
         switch (packet)
         {

Source/MQTTnet/Protocol/MqttTopicValidator.cs

@@ -11,10 +11,7 @@ namespace MQTTnet.Protocol
     {
         public static void ThrowIfInvalid(MqttApplicationMessage applicationMessage)
         {
-            if (applicationMessage == null)
+            ArgumentNullException.ThrowIfNull(applicationMessage);
-            {
-                throw new ArgumentNullException(nameof(applicationMessage));
-            }
 
             if (applicationMessage.TopicAlias == 0)
             {

Source/MQTTnet/Subscribing/MqttClientSubscribeOptionsBuilder.cs

@@ -50,10 +50,7 @@ public sealed class MqttClientSubscribeOptionsBuilder
 
     public MqttClientSubscribeOptionsBuilder WithTopicFilter(Action<MqttTopicFilterBuilder> topicFilterBuilder)
     {
-        if (topicFilterBuilder == null)
+        ArgumentNullException.ThrowIfNull(topicFilterBuilder);
-        {
-            throw new ArgumentNullException(nameof(topicFilterBuilder));
-        }
 
         var internalTopicFilterBuilder = new MqttTopicFilterBuilder();
         topicFilterBuilder(internalTopicFilterBuilder);
@@ -63,20 +60,14 @@ public sealed class MqttClientSubscribeOptionsBuilder
 
     public MqttClientSubscribeOptionsBuilder WithTopicFilter(MqttTopicFilterBuilder topicFilterBuilder)
     {
-        if (topicFilterBuilder == null)
+        ArgumentNullException.ThrowIfNull(topicFilterBuilder);
-        {
-            throw new ArgumentNullException(nameof(topicFilterBuilder));
-        }
 
         return WithTopicFilter(topicFilterBuilder.Build());
     }
 
     public MqttClientSubscribeOptionsBuilder WithTopicFilter(MqttTopicFilter topicFilter)
     {
-        if (topicFilter == null)
+        ArgumentNullException.ThrowIfNull(topicFilter);
-        {
-            throw new ArgumentNullException(nameof(topicFilter));
-        }
 
         if (_subscribeOptions.TopicFilters == null)
         {

Source/MQTTnet/Subscribing/MqttClientSubscribeOptionsValidator.cs

@@ -13,10 +13,7 @@ public static class MqttClientSubscribeOptionsValidator
 {
     public static void ThrowIfNotSupported(MqttClientSubscribeOptions options, MqttProtocolVersion protocolVersion)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         if (protocolVersion == MqttProtocolVersion.V500)
         {

Source/MQTTnet/Subscribing/MqttClientSubscribeResultFactory.cs

@@ -16,15 +16,8 @@ public sealed class MqttClientSubscribeResultFactory
 
     public MqttClientSubscribeResult Create(MqttSubscribePacket subscribePacket, MqttSubAckPacket subAckPacket)
     {
-        if (subscribePacket == null)
+        ArgumentNullException.ThrowIfNull(subscribePacket);
-        {
+        ArgumentNullException.ThrowIfNull(subAckPacket);
-            throw new ArgumentNullException(nameof(subscribePacket));
-        }
-
-        if (subAckPacket == null)
-        {
-            throw new ArgumentNullException(nameof(subAckPacket));
-        }
 
         // MQTTv5.0.0 handling.
         if (subAckPacket.ReasonCodes.Any() && subAckPacket.ReasonCodes.Count != subscribePacket.TopicFilters.Count)

Source/MQTTnet/Unsubscribing/MqttClientUnsubscribeOptionsBuilder.cs

@@ -19,10 +19,7 @@ public sealed class MqttClientUnsubscribeOptionsBuilder
 
     public MqttClientUnsubscribeOptionsBuilder WithTopicFilter(string topic)
     {
-        if (topic is null)
+        ArgumentNullException.ThrowIfNull(topic);
-        {
-            throw new ArgumentNullException(nameof(topic));
-        }
 
         if (_unsubscribeOptions.TopicFilters is null)
         {
@@ -36,10 +33,7 @@ public sealed class MqttClientUnsubscribeOptionsBuilder
 
     public MqttClientUnsubscribeOptionsBuilder WithTopicFilter(MqttTopicFilter topicFilter)
     {
-        if (topicFilter is null)
+        ArgumentNullException.ThrowIfNull(topicFilter);
-        {
-            throw new ArgumentNullException(nameof(topicFilter));
-        }
 
         return WithTopicFilter(topicFilter.Topic);
     }
@@ -59,10 +53,7 @@ public sealed class MqttClientUnsubscribeOptionsBuilder
     /// </summary>
     public MqttClientUnsubscribeOptionsBuilder WithUserProperty(MqttUserProperty userProperty)
     {
-        if (userProperty is null)
+        ArgumentNullException.ThrowIfNull(userProperty);
-        {
-            throw new ArgumentNullException(nameof(userProperty));
-        }
 
         if (_unsubscribeOptions.UserProperties is null)
         {

Source/MQTTnet/Unsubscribing/MqttClientUnsubscribeOptionsValidator.cs

@@ -12,10 +12,7 @@ public static class MqttClientUnsubscribeOptionsValidator
 {
     public static void ThrowIfNotSupported(MqttClientUnsubscribeOptions options, MqttProtocolVersion protocolVersion)
     {
-        if (options == null)
+        ArgumentNullException.ThrowIfNull(options);
-        {
-            throw new ArgumentNullException(nameof(options));
-        }
 
         if (protocolVersion == MqttProtocolVersion.V500)
         {

Source/MQTTnet/Unsubscribing/MqttClientUnsubscribeResultFactory.cs

@@ -15,15 +15,8 @@ public sealed class MqttClientUnsubscribeResultFactory
 
     public MqttClientUnsubscribeResult Create(MqttUnsubscribePacket unsubscribePacket, MqttUnsubAckPacket unsubAckPacket)
     {
-        if (unsubscribePacket == null)
+        ArgumentNullException.ThrowIfNull(unsubscribePacket);
-        {
+        ArgumentNullException.ThrowIfNull(unsubAckPacket);
-            throw new ArgumentNullException(nameof(unsubscribePacket));
-        }
-
-        if (unsubAckPacket == null)
-        {
-            throw new ArgumentNullException(nameof(unsubAckPacket));
-        }
 
         // MQTTv3.1.1 has no reason code at all!
         if (unsubAckPacket.ReasonCodes != null && unsubAckPacket.ReasonCodes.Count != unsubscribePacket.TopicFilters.Count)