Enable nullable

Source/MQTTnet.Extensions.Rpc/IMqttRpcClient.cs

@@ -12,7 +12,12 @@ namespace MQTTnet.Extensions.Rpc;
 
 public interface IMqttRpcClient : IDisposable
 {
-    Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, IDictionary<string,object> parameters = null);
+    Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, IDictionary<string, object>? parameters = null);
 
-    Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, IDictionary<string, object> parameters = null, CancellationToken cancellationToken = default);
+    Task<byte[]> ExecuteAsync(
+        string methodName,
+        byte[] payload,
+        MqttQualityOfServiceLevel qualityOfServiceLevel,
+        IDictionary<string, object>? parameters = null,
+        CancellationToken cancellationToken = default);
 }

Source/MQTTnet.Extensions.Rpc/MQTTnet.Extensions.Rpc.csproj

@@ -37,6 +37,8 @@
         <NuGetAuditLevel>low</NuGetAuditLevel>
         <AnalysisLevel>latest-Recommended</AnalysisLevel>
         <IsAotCompatible>true</IsAotCompatible>
+        <LangVersion>default</LangVersion>
+        <Nullable>enable</Nullable>
     </PropertyGroup>
 
     <ItemGroup>

Source/MQTTnet.Extensions.Rpc/MqttRpcClient.cs

@@ -20,7 +20,7 @@ public sealed class MqttRpcClient : IMqttRpcClient
     readonly IMqttClient _mqttClient;
     readonly MqttRpcClientOptions _options;
 
-    readonly ConcurrentDictionary<string, AsyncTaskCompletionSource<byte[]>> _waitingCalls = new ConcurrentDictionary<string, AsyncTaskCompletionSource<byte[]>>();
+    readonly ConcurrentDictionary<string, AsyncTaskCompletionSource<byte[]>> _waitingCalls = new();
 
     public MqttRpcClient(IMqttClient mqttClient, MqttRpcClientOptions options)
     {
@@ -42,7 +42,12 @@ public sealed class MqttRpcClient : IMqttRpcClient
         _waitingCalls.Clear();
     }
 
-    public async Task<byte[]> ExecuteAsync(TimeSpan timeout, string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, IDictionary<string, object> parameters = null)
+    public async Task<byte[]> ExecuteAsync(
+        TimeSpan timeout,
+        string methodName,
+        byte[] payload,
+        MqttQualityOfServiceLevel qualityOfServiceLevel,
+        IDictionary<string, object>? parameters = null)
     {
         using var timeoutToken = new CancellationTokenSource(timeout);
         try
@@ -60,7 +65,12 @@ public sealed class MqttRpcClient : IMqttRpcClient
         }
     }
 
-    public async Task<byte[]> ExecuteAsync(string methodName, byte[] payload, MqttQualityOfServiceLevel qualityOfServiceLevel, IDictionary<string, object> parameters = null, CancellationToken cancellationToken = default)
+    public async Task<byte[]> ExecuteAsync(
+        string methodName,
+        byte[] payload,
+        MqttQualityOfServiceLevel qualityOfServiceLevel,
+        IDictionary<string, object>? parameters = null,
+        CancellationToken cancellationToken = default)
     {
         ArgumentNullException.ThrowIfNull(methodName);
 
@@ -82,7 +92,7 @@ public sealed class MqttRpcClient : IMqttRpcClient
 
         var requestMessageBuilder = new MqttApplicationMessageBuilder().WithTopic(requestTopic).WithPayload(payload).WithQualityOfServiceLevel(qualityOfServiceLevel);
 
-        if (_mqttClient.Options.ProtocolVersion == MqttProtocolVersion.V500)
+        if (_mqttClient.Options!.ProtocolVersion == MqttProtocolVersion.V500)
         {
             requestMessageBuilder.WithResponseTopic(responseTopic);
         }
@@ -103,11 +113,10 @@ public sealed class MqttRpcClient : IMqttRpcClient
             await _mqttClient.SubscribeAsync(subscribeOptions, cancellationToken).ConfigureAwait(false);
             await _mqttClient.PublishAsync(requestMessage, cancellationToken).ConfigureAwait(false);
 
-            using (cancellationToken.Register(
-                       () =>
-                       {
-                           awaitable.TrySetCanceled();
-                       }))
+            using (cancellationToken.Register(() =>
+                   {
+                       awaitable.TrySetCanceled();
+                   }))
             {
                 return await awaitable.Task.ConfigureAwait(false);
             }

Source/MQTTnet.Extensions.Rpc/MqttRpcClientExtensions.cs

@@ -12,7 +12,7 @@ namespace MQTTnet.Extensions.Rpc;
 
 public static class MqttRpcClientExtensions
 {
-    public static Task<byte[]> ExecuteAsync(this IMqttRpcClient client, TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel, IDictionary<string,object> parameters = null)
+    public static Task<byte[]> ExecuteAsync(this IMqttRpcClient client, TimeSpan timeout, string methodName, string payload, MqttQualityOfServiceLevel qualityOfServiceLevel, IDictionary<string,object>? parameters = null)
     {
         if (client == null) throw new ArgumentNullException(nameof(client));
 

Source/MQTTnet.Extensions.Rpc/MqttRpcTopicPair.cs

@@ -6,7 +6,7 @@ namespace MQTTnet.Extensions.Rpc;
 
 public sealed class MqttRpcTopicPair
 {
-    public string RequestTopic { get; set; }
+    public required string RequestTopic { get; init; }
 
-    public string ResponseTopic { get; set; }
+    public required string ResponseTopic { get; init; }
 }

Source/MQTTnet.Extensions.Rpc/TopicGenerationContext.cs

@@ -10,8 +10,12 @@ namespace MQTTnet.Extensions.Rpc;
 
 public sealed class TopicGenerationContext
 {
-    public TopicGenerationContext(IMqttClient mqttClient, MqttRpcClientOptions options, string methodName,
-        IDictionary<string, object> parameters, MqttQualityOfServiceLevel qualityOfServiceLevel)
+    public TopicGenerationContext(
+        IMqttClient mqttClient,
+        MqttRpcClientOptions options,
+        string methodName,
+        IDictionary<string, object>? parameters,
+        MqttQualityOfServiceLevel qualityOfServiceLevel)
     {
         MethodName = methodName ?? throw new ArgumentNullException(nameof(methodName));
         Parameters = parameters;
@@ -22,12 +26,12 @@ public sealed class TopicGenerationContext
 
     public string MethodName { get; }
 
-    public IDictionary<string, object> Parameters { get; }
-
     public IMqttClient MqttClient { get; }
 
     public MqttRpcClientOptions Options { get; }
 
+    public IDictionary<string, object>? Parameters { get; }
+
     /// <summary>
     ///     Gets or sets the quality of service level.
     ///     The Quality of Service (QoS) level is an agreement between the sender of a message and the receiver of a message