Enable Nullable on the solution (#1753)

* Enable nullable

* Approve API changes

* Add validation to AuthMechanisms property

* Improve property validation messages

* Use factory method to create ConfirmsAwareChannel

* Refine null check for message header lookup in `SendMessage`.

* Simplify `PublishMessage` and `RawSendInCaseOfFailure` methods by converting to expression-bodied implementations.

* Refine header lookup and initialization in `MessagePump` for improved null safety and cleaner logic.

* Simplify `Channel_ModelShutdown` logic by consolidating conditional checks.

---------

Co-authored-by: Daniel Marbach <danielmarbach@users.noreply.github.com>

Author: bording

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/ChannelExtensions.cs

@@ -1,4 +1,6 @@
-namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
+#nullable enable
+
+namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
 {
     using System.Collections.Generic;
     using System.Threading.Tasks;
@@ -8,7 +10,7 @@ static class ChannelExtensions
     {
         public static Task<QueueDeclareOk> DeclareQuorumQueue(this IChannel channel, string queueName)
         {
-            return channel.QueueDeclareAsync(queueName, true, false, false, new Dictionary<string, object>
+            return channel.QueueDeclareAsync(queueName, true, false, false, new Dictionary<string, object?>
             {
                 { "x-queue-type", "quorum" }
             });

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/ConfigurationHelpers.cs

@@ -1,4 +1,6 @@
-using NServiceBus;
+#nullable enable
+
+using NServiceBus;
 using NServiceBus.AcceptanceTests.EndpointTemplates;
 
 static class ConfigurationHelpers

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/ConfigureEndpointRabbitMQTransport.cs

@@ -1,4 +1,6 @@
-using System;
+#nullable enable
+
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading;
@@ -10,7 +12,7 @@
 
 class ConfigureEndpointRabbitMQTransport : IConfigureEndpointTestExecution
 {
-    TestRabbitMQTransport transport;
+    TestRabbitMQTransport? transport;
     readonly QueueType queueType;
 
     public ConfigureEndpointRabbitMQTransport(QueueType queueType = QueueType.Classic)
@@ -20,7 +22,7 @@ public ConfigureEndpointRabbitMQTransport(QueueType queueType = QueueType.Classi
 
     public Task Configure(string endpointName, EndpointConfiguration configuration, RunSettings settings, PublisherMetadata publisherMetadata)
     {
-        transport = new TestRabbitMQTransport(RoutingTopology.Conventional(queueType, type => type.FullName), ConnectionHelper.ConnectionString)
+        transport = new TestRabbitMQTransport(RoutingTopology.Conventional(queueType, type => type.FullName!), ConnectionHelper.ConnectionString)
         {
             // The startup costs for creating a policy for every test queue add up, and the tests shouldn't be impacted by the default delivery limit.
             ValidateDeliveryLimits = false

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/ConnectionHelper.cs

@@ -1,4 +1,6 @@
-namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
+#nullable enable
+
+namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
 {
     using System;
     using System.Security.Authentication;

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/DelayedDelivery/When_deferring_a_message_longer_than_allowed_maximum.cs

@@ -1,4 +1,6 @@
-namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests.DelayedDelivery
+#nullable enable
+
+namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests.DelayedDelivery
 {
     using System;
     using System.Threading.Tasks;

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/QuorumEndpoint.cs

@@ -1,4 +1,6 @@
-namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
+#nullable enable
+
+namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
 {
     using NServiceBus.AcceptanceTests.EndpointTemplates;
 

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/QuorumQueues/When_classic_endpoint_uses_quorum_error_queue.cs

@@ -1,4 +1,6 @@
-namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
+#nullable enable
+
+namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
 {
     using System;
     using System.Threading.Tasks;

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/QuorumQueues/When_classic_endpoint_uses_quorum_queue.cs

@@ -1,4 +1,6 @@
-namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
+#nullable enable
+
+namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
 {
     using System;
     using System.Threading.Tasks;

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/QuorumQueues/When_immediate_retries_with_quorum_queues.cs

@@ -1,4 +1,6 @@
-namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
+#nullable enable
+
+namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
 {
     using System;
     using System.Linq;
@@ -23,8 +25,7 @@ public async Task Should_do_the_configured_number_of_retries()
             {
                 Assert.That(context.ForwardedToErrorQueue, Is.True);
                 Assert.That(context.NumberOfTimesInvoked, Is.EqualTo(numberOfRetries + 1), "Message should be retried 5 times immediately");
-                Assert.That(context.Logs.Count(l => l.Message
-                    .StartsWith($"Immediate Retry is going to retry message '{context.MessageId}' because of an exception:")), Is.EqualTo(numberOfRetries));
+                Assert.That(context.Logs.Count(l => l.Message?.StartsWith($"Immediate Retry is going to retry message '{context.MessageId}' because of an exception:") ?? false), Is.EqualTo(numberOfRetries));
             });
         }
 
@@ -36,7 +37,7 @@ class Context : ScenarioContext
 
             public bool ForwardedToErrorQueue { get; set; }
 
-            public string MessageId { get; set; }
+            public string? MessageId { get; set; }
         }
 
         public class RetryEndpoint : EndpointConfigurationBuilder

src/NServiceBus.Transport.RabbitMQ.AcceptanceTests/QuorumQueues/When_quorum_endpoint_uses_classic_error_queue.cs

@@ -1,4 +1,6 @@
-namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
+#nullable enable
+
+namespace NServiceBus.Transport.RabbitMQ.AcceptanceTests
 {
     using System;
     using System.Threading.Tasks;