feat: upgrade to C#9.0

Author: Christoph Bühler

src/KubeOps/Build/Program.cs

@@ -4,6 +4,6 @@ namespace KubeOps.Build
 {
     internal static class Program
     {
-        public static Task Main(string[] _) => Task.CompletedTask;
+        public static Task Main() => Task.CompletedTask;
     }
 }

src/KubeOps/Operator/Caching/CacheComparisonResult.cs

@@ -1,5 +1,8 @@
 namespace KubeOps.Operator.Caching
 {
+    /// <summary>
+    /// Result for the <see cref="IResourceCache{TEntity}.Upsert"/> when comparison is done.
+    /// </summary>
     public enum CacheComparisonResult
     {
         /// <summary>

src/KubeOps/Operator/Caching/ResourceCache.cs

@@ -17,7 +17,7 @@ internal class ResourceCache<TEntity> : IResourceCache<TEntity>
         private const string Finalizers = "Metadata.Finalizers";
         private const string Status = "Status";
 
-        private readonly CompareLogic _compare = new CompareLogic(
+        private readonly CompareLogic _compare = new(
             new ComparisonConfig
             {
                 Caching = true,

src/KubeOps/Operator/Comparing/ArrayExtensions.cs

@@ -11,7 +11,7 @@ public static void ForEach(this Array array, Action<Array, int[]> action)
                 return;
             }
 
-            ArrayTraverse walker = new ArrayTraverse(array);
+            ArrayTraverse walker = new(array);
             do
             {
                 action(array, walker.Position);

src/KubeOps/Operator/Entities/CustomKubernetesEntity.cs

@@ -8,6 +8,6 @@ namespace KubeOps.Operator.Entities
     /// </summary>
     public abstract class CustomKubernetesEntity : KubernetesObject, IKubernetesObject<V1ObjectMeta>
     {
-        public V1ObjectMeta Metadata { get; set; } = new V1ObjectMeta();
+        public V1ObjectMeta Metadata { get; set; } = new();
     }
 }

src/KubeOps/Operator/Entities/CustomKubernetesEntity{TSpec,TStatus}.cs

@@ -14,6 +14,6 @@ public abstract class CustomKubernetesEntity<TSpec, TStatus> : CustomKubernetesE
         where TSpec : new()
         where TStatus : new()
     {
-        public TStatus Status { get; set; } = new TStatus();
+        public TStatus Status { get; set; } = new();
     }
 }

src/KubeOps/Operator/Entities/CustomKubernetesEntity{TSpec}.cs

@@ -10,6 +10,6 @@ namespace KubeOps.Operator.Entities
     public abstract class CustomKubernetesEntity<TSpec> : CustomKubernetesEntity, ISpec<TSpec>
         where TSpec : new()
     {
-        public TSpec Spec { get; set; } = new TSpec();
+        public TSpec Spec { get; set; } = new();
     }
 }

src/KubeOps/Operator/Entities/EntityList.cs

@@ -7,7 +7,7 @@ namespace KubeOps.Operator.Entities
     public class EntityList<T> : KubernetesObject
         where T : IKubernetesObject<V1ObjectMeta>
     {
-        public V1ListMeta Metadata { get; set; } = new V1ListMeta();
+        public V1ListMeta Metadata { get; set; } = new();
 
         public IList<T> Items { get; set; } = new List<T>();
     }

src/KubeOps/Operator/Errors/ExponentialBackoffHandler.cs

@@ -10,7 +10,7 @@ internal class ExponentialBackoffHandler : IDisposable
         private const double MaxRetrySeconds = 64;
         private readonly Action? _retryHandler;
         private readonly Func<Task>? _asyncRetryHandler;
-        private readonly Random _rnd = new Random();
+        private readonly Random _rnd = new();
 
         private Timer? _retryTimer;
         private Timer? _resetTimer;

src/KubeOps/Operator/Queue/ResourceEventQueue.cs

@@ -23,7 +23,7 @@ internal class ResourceEventQueue<TEntity> : IResourceEventQueue<TEntity>
         private readonly Channel<(ResourceEventType Type, TEntity Resource)> _queue =
             Channel.CreateBounded<(ResourceEventType Type, TEntity Resource)>(QueueLimit);
 
-        private readonly SemaphoreSlim _semaphore = new SemaphoreSlim(1);
+        private readonly SemaphoreSlim _semaphore = new(1);
         private readonly ILogger<ResourceEventQueue<TEntity>> _logger;
         private readonly IKubernetesClient _client;
         private readonly IResourceCache<TEntity> _cache;
@@ -32,8 +32,7 @@ internal class ResourceEventQueue<TEntity> : IResourceEventQueue<TEntity>
         private readonly IDictionary<string, ResourceTimer<TEntity>> _delayedEnqueue =
             new ConcurrentDictionary<string, ResourceTimer<TEntity>>();
 
-        private readonly ConcurrentDictionary<string, ExponentialBackoffHandler> _errorHandlers =
-            new ConcurrentDictionary<string, ExponentialBackoffHandler>();
+        private readonly ConcurrentDictionary<string, ExponentialBackoffHandler> _errorHandlers = new();
 
         private readonly ResourceEventQueueMetrics<TEntity> _metrics;