Use is null instead of == null (#1565)

* Use is null instead of == null

* Use is null in new code

Co-authored-by: Miha Zupan <mihazupan.zupan1@gmail.com>

docs/docfx/articles/dests-health-checks.md

@@ -139,7 +139,7 @@ public class FirstUnsuccessfulResponseHealthPolicy : IActiveHealthCheckPolicy
         for (var i = 0; i < probingResults.Count; i++)
         {
             var response = probingResults[i].Response;
-            var newHealth = response != null && response.IsSuccessStatusCode ? DestinationHealth.Healthy : DestinationHealth.Unhealthy;
+            var newHealth = response is not null && response.IsSuccessStatusCode ? DestinationHealth.Healthy : DestinationHealth.Unhealthy;
             newHealthStates[i] = new NewActiveDestinationHealth(probingResults[i].Destination, newHealth);
         }
 
@@ -317,7 +317,7 @@ public class FirstUnsuccessfulResponseHealthPolicy : IPassiveHealthCheckPolicy
     public void RequestProxied(ClusterState cluster, DestinationState destination, HttpContext context)
     {
         var error = context.Features.Get<IProxyErrorFeature>();
-        if (error != null)
+        if (error is not null)
         {
             var reactivationPeriod = cluster.Model.Config.HealthCheck.Passive.ReactivationPeriod ?? _defaultReactivationPeriod;
             _ = _healthUpdater.SetPassiveAsync(cluster, destination, DestinationHealth.Unhealthy, reactivationPeriod);

docs/docfx/articles/middleware.md

@@ -137,7 +137,7 @@ proxyPipeline.Use(async (context, next) =>
     await next();
 
     var errorFeature = context.GetForwarderErrorFeature();
-    if (errorFeature != null)
+    if (errorFeature is not null)
     {
         Report(errorFeature.Error, errorFeature.Exception);
     }

src/Kubernetes.Controller/Caching/IngressCache.cs

@@ -145,7 +145,7 @@ public class IngressCache : ICache
 
     private bool IsYarpIngress(V1IngressSpec spec)
     {
-        if (spec.IngressClassName != null)
+        if (spec.IngressClassName is not null)
         {
             lock (_sync)
             {

src/Kubernetes.Controller/Converters/YarpParser.cs

@@ -90,7 +90,7 @@ internal static class YarpParser
                 {
                     Match = new RouteMatch()
                     {
-                        Hosts = host != null ? new[] { host } : Array.Empty<string>(),
+                        Hosts = host is not null ? new[] { host } : Array.Empty<string>(),
                         Path = pathMatch
                     },
                     ClusterId = cluster.ClusterId,
@@ -117,7 +117,7 @@ internal static class YarpParser
 
     private static string UpstreamName(string namespaceName, V1IngressServiceBackend ingressServiceBackend)
     {
-        if (ingressServiceBackend != null)
+        if (ingressServiceBackend is not null)
         {
             if (ingressServiceBackend.Port.Number.HasValue && ingressServiceBackend.Port.Number.Value > 0)
             {
@@ -156,7 +156,7 @@ internal static class YarpParser
     {
         var options = context.Options;
         var annotations = metadata.Annotations;
-        if (annotations == null)
+        if (annotations is null)
         {
             return options;
         }
@@ -216,7 +216,7 @@ internal static class YarpParser
 
     private static bool MatchesPort(Corev1EndpointPort port1, IntstrIntOrString port2)
     {
-        if (port1 == null || port2 == null)
+        if (port1 is null || port2 is null)
         {
             return false;
         }
@@ -233,15 +233,15 @@ internal static class YarpParser
 
     private static bool MatchesPort(V1ServicePort port1, V1ServiceBackendPort port2)
     {
-        if (port1 == null || port2 == null)
+        if (port1 is null || port2 is null)
         {
             return false;
         }
-        if (port2.Number != null && port2.Number == port1.Port)
+        if (port2.Number is not null && port2.Number == port1.Port)
         {
             return true;
         }
-        if (port2.Name != null && string.Equals(port2.Name, port1.Name, StringComparison.Ordinal))
+        if (port2.Name is not null && string.Equals(port2.Name, port1.Name, StringComparison.Ordinal))
         {
             return true;
         }

src/Kubernetes.Protocol/MessageConfigProviderExtensions.cs

@@ -11,7 +11,7 @@ public static class MessageConfigProviderExtensions
 {
     public static IReverseProxyBuilder LoadFromMessages(this IReverseProxyBuilder builder)
     {
-        if (builder == null)
+        if (builder is null)
         {
             throw new ArgumentNullException(nameof(builder));
         }

src/OperatorFramework/src/Controller/Informers/ResourceInformer.cs

@@ -405,7 +405,7 @@ namespace Microsoft.Kubernetes.Controller.Informers
                 catch (Exception innerException)
 #pragma warning restore CA1031 // Do not catch general exception types
                 {
-                    if (innerExceptions == null)
+                    if (innerExceptions is null)
                     {
                         innerExceptions = new List<Exception>();
                     }
@@ -414,7 +414,7 @@ namespace Microsoft.Kubernetes.Controller.Informers
                 }
             }
 
-            if (innerExceptions != null)
+            if (innerExceptions is not null)
             {
                 throw new AggregateException("One or more exceptions thrown by ResourceInformerCallback.", innerExceptions);
             }

src/OperatorFramework/src/Core/Client/AnyResourceKind.cs

@@ -59,15 +59,15 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
 
     public async Task<HttpOperationResponse<KubernetesList<TResource>>> ListClusterAnyResourceKindWithHttpMessagesAsync<TResource>(string group, string version, string plural, string continueParameter = null, string fieldSelector = null, string labelSelector = null, int? limit = null, string resourceVersion = null, int? timeoutSeconds = null, bool? watch = null, string pretty = null, Dictionary<string, List<string>> customHeaders = null, CancellationToken cancellationToken = default) where TResource : IKubernetesObject
     {
-        if (group == null)
+        if (group is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "group");
         }
-        if (version == null)
+        if (version is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "version");
         }
-        if (plural == null)
+        if (plural is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "plural");
         }
@@ -109,35 +109,35 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         _url = _url.Replace("{version}", System.Uri.EscapeDataString(version));
         _url = _url.Replace("{plural}", System.Uri.EscapeDataString(plural));
         List<string> _queryParameters = new List<string>();
-        if (continueParameter != null)
+        if (continueParameter is not null)
         {
             _queryParameters.Add(string.Format("continue={0}", System.Uri.EscapeDataString(continueParameter)));
         }
-        if (fieldSelector != null)
+        if (fieldSelector is not null)
         {
             _queryParameters.Add(string.Format("fieldSelector={0}", System.Uri.EscapeDataString(fieldSelector)));
         }
-        if (labelSelector != null)
+        if (labelSelector is not null)
         {
             _queryParameters.Add(string.Format("labelSelector={0}", System.Uri.EscapeDataString(labelSelector)));
         }
-        if (limit != null)
+        if (limit is not null)
         {
             _queryParameters.Add(string.Format("limit={0}", System.Uri.EscapeDataString(SafeJsonConvert.SerializeObject(limit, Client.SerializationSettings).Trim('"'))));
         }
-        if (resourceVersion != null)
+        if (resourceVersion is not null)
         {
             _queryParameters.Add(string.Format("resourceVersion={0}", System.Uri.EscapeDataString(resourceVersion)));
         }
-        if (timeoutSeconds != null)
+        if (timeoutSeconds is not null)
         {
             _queryParameters.Add(string.Format("timeoutSeconds={0}", System.Uri.EscapeDataString(SafeJsonConvert.SerializeObject(timeoutSeconds, Client.SerializationSettings).Trim('"'))));
         }
-        if (watch != null)
+        if (watch is not null)
         {
             _queryParameters.Add(string.Format("watch={0}", System.Uri.EscapeDataString(SafeJsonConvert.SerializeObject(watch, Client.SerializationSettings).Trim('"'))));
         }
-        if (pretty != null)
+        if (pretty is not null)
         {
             _queryParameters.Add(string.Format("pretty={0}", System.Uri.EscapeDataString(pretty)));
         }
@@ -153,7 +153,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         // Set Headers
 
 
-        if (customHeaders != null)
+        if (customHeaders is not null)
         {
             foreach (var _header in customHeaders)
             {
@@ -168,7 +168,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         // Serialize Request
         string _requestContent = null;
         // Set Credentials
-        if (Client.Credentials != null)
+        if (Client.Credentials is not null)
         {
             cancellationToken.ThrowIfCancellationRequested();
             await Client.Credentials.ProcessHttpRequestAsync(_httpRequest, cancellationToken).ConfigureAwait(false);
@@ -190,7 +190,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         if ((int)_statusCode != 200)
         {
             var ex = new HttpOperationException(string.Format("Operation returned an invalid status code '{0}'", _statusCode));
-            if (_httpResponse.Content != null)
+            if (_httpResponse.Content is not null)
             {
                 _responseContent = await _httpResponse.Content.ReadAsStringAsync().ConfigureAwait(false);
             }
@@ -205,7 +205,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
                 ServiceClientTracing.Error(_invocationId, ex);
             }
             _httpRequest.Dispose();
-            if (_httpResponse != null)
+            if (_httpResponse is not null)
             {
                 _httpResponse.Dispose();
             }
@@ -226,7 +226,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
             catch (Newtonsoft.Json.JsonException ex)
             {
                 _httpRequest.Dispose();
-                if (_httpResponse != null)
+                if (_httpResponse is not null)
                 {
                     _httpResponse.Dispose();
                 }
@@ -243,23 +243,23 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
 
     public async Task<HttpOperationResponse<object>> CreateAnyResourceKindWithHttpMessagesAsync<TResource>(TResource body, string group, string version, string namespaceParameter, string plural, string dryRun = default(string), string fieldManager = default(string), string pretty = default(string), Dictionary<string, List<string>> customHeaders = null, CancellationToken cancellationToken = default(CancellationToken)) where TResource : IKubernetesObject
     {
-        if (body == null)
+        if (body is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "body");
         }
-        if (group == null)
+        if (group is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "group");
         }
-        if (version == null)
+        if (version is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "version");
         }
-        if (namespaceParameter == null)
+        if (namespaceParameter is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "namespaceParameter");
         }
-        if (plural == null)
+        if (plural is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "plural");
         }
@@ -289,15 +289,15 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         _url = _url.Replace("{namespace}", System.Uri.EscapeDataString(namespaceParameter));
         _url = _url.Replace("{plural}", System.Uri.EscapeDataString(plural));
         List<string> _queryParameters = new List<string>();
-        if (dryRun != null)
+        if (dryRun is not null)
         {
             _queryParameters.Add(string.Format("dryRun={0}", System.Uri.EscapeDataString(dryRun)));
         }
-        if (fieldManager != null)
+        if (fieldManager is not null)
         {
             _queryParameters.Add(string.Format("fieldManager={0}", System.Uri.EscapeDataString(fieldManager)));
         }
-        if (pretty != null)
+        if (pretty is not null)
         {
             _queryParameters.Add(string.Format("pretty={0}", System.Uri.EscapeDataString(pretty)));
         }
@@ -313,7 +313,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         // Set Headers
 
 
-        if (customHeaders != null)
+        if (customHeaders is not null)
         {
             foreach (var _header in customHeaders)
             {
@@ -327,14 +327,14 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
 
         // Serialize Request
         string _requestContent = null;
-        if (body != null)
+        if (body is not null)
         {
             _requestContent = SafeJsonConvert.SerializeObject(body, Client.SerializationSettings);
             _httpRequest.Content = new StringContent(_requestContent, System.Text.Encoding.UTF8);
             _httpRequest.Content.Headers.ContentType = Client.GetHeader(body);
         }
         // Set Credentials
-        if (Client.Credentials != null)
+        if (Client.Credentials is not null)
         {
             cancellationToken.ThrowIfCancellationRequested();
             await Client.Credentials.ProcessHttpRequestAsync(_httpRequest, cancellationToken).ConfigureAwait(false);
@@ -356,7 +356,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         if ((int)_statusCode != 201)
         {
             var ex = new HttpOperationException(string.Format("Operation returned an invalid status code '{0}'", _statusCode));
-            if (_httpResponse.Content != null)
+            if (_httpResponse.Content is not null)
             {
                 _responseContent = await _httpResponse.Content.ReadAsStringAsync().ConfigureAwait(false);
             }
@@ -371,7 +371,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
                 ServiceClientTracing.Error(_invocationId, ex);
             }
             _httpRequest.Dispose();
-            if (_httpResponse != null)
+            if (_httpResponse is not null)
             {
                 _httpResponse.Dispose();
             }
@@ -392,7 +392,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
             catch (JsonException ex)
             {
                 _httpRequest.Dispose();
-                if (_httpResponse != null)
+                if (_httpResponse is not null)
                 {
                     _httpResponse.Dispose();
                 }
@@ -409,27 +409,27 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
 
     public async Task<HttpOperationResponse<object>> PatchAnyResourceKindWithHttpMessagesAsync(V1Patch body, string group, string version, string namespaceParameter, string plural, string name, string dryRun = default(string), string fieldManager = default(string), bool? force = default(bool?), Dictionary<string, List<string>> customHeaders = null, CancellationToken cancellationToken = default(CancellationToken))
     {
-        if (body == null)
+        if (body is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "body");
         }
-        if (group == null)
+        if (group is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "group");
         }
-        if (version == null)
+        if (version is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "version");
         }
-        if (namespaceParameter == null)
+        if (namespaceParameter is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "namespaceParameter");
         }
-        if (plural == null)
+        if (plural is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "plural");
         }
-        if (name == null)
+        if (name is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "name");
         }
@@ -461,15 +461,15 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         _url = _url.Replace("{plural}", System.Uri.EscapeDataString(plural));
         _url = _url.Replace("{name}", System.Uri.EscapeDataString(name));
         List<string> _queryParameters = new List<string>();
-        if (dryRun != null)
+        if (dryRun is not null)
         {
             _queryParameters.Add(string.Format("dryRun={0}", System.Uri.EscapeDataString(dryRun)));
         }
-        if (fieldManager != null)
+        if (fieldManager is not null)
         {
             _queryParameters.Add(string.Format("fieldManager={0}", System.Uri.EscapeDataString(fieldManager)));
         }
-        if (force != null)
+        if (force is not null)
         {
             _queryParameters.Add(string.Format("force={0}", System.Uri.EscapeDataString(SafeJsonConvert.SerializeObject(force, Client.SerializationSettings).Trim('"'))));
         }
@@ -485,7 +485,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         // Set Headers
 
 
-        if (customHeaders != null)
+        if (customHeaders is not null)
         {
             foreach (var _header in customHeaders)
             {
@@ -499,14 +499,14 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
 
         // Serialize Request
         string _requestContent = null;
-        if (body != null)
+        if (body is not null)
         {
             _requestContent = SafeJsonConvert.SerializeObject(body, Client.SerializationSettings);
             _httpRequest.Content = new StringContent(_requestContent, System.Text.Encoding.UTF8);
             _httpRequest.Content.Headers.ContentType = Client.GetHeader(body);
         }
         // Set Credentials
-        if (Client.Credentials != null)
+        if (Client.Credentials is not null)
         {
             cancellationToken.ThrowIfCancellationRequested();
             await Client.Credentials.ProcessHttpRequestAsync(_httpRequest, cancellationToken).ConfigureAwait(false);
@@ -528,7 +528,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         if ((int)_statusCode != 200)
         {
             var ex = new HttpOperationException(string.Format("Operation returned an invalid status code '{0}'", _statusCode));
-            if (_httpResponse.Content != null)
+            if (_httpResponse.Content is not null)
             {
                 _responseContent = await _httpResponse.Content.ReadAsStringAsync().ConfigureAwait(false);
             }
@@ -543,7 +543,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
                 ServiceClientTracing.Error(_invocationId, ex);
             }
             _httpRequest.Dispose();
-            if (_httpResponse != null)
+            if (_httpResponse is not null)
             {
                 _httpResponse.Dispose();
             }
@@ -564,7 +564,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
             catch (JsonException ex)
             {
                 _httpRequest.Dispose();
-                if (_httpResponse != null)
+                if (_httpResponse is not null)
                 {
                     _httpResponse.Dispose();
                 }
@@ -581,23 +581,23 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
 
     public async Task<HttpOperationResponse<object>> DeleteAnyResourceKindWithHttpMessagesAsync(string group, string version, string namespaceParameter, string plural, string name, V1DeleteOptions body = default(V1DeleteOptions), int? gracePeriodSeconds = default(int?), bool? orphanDependents = default(bool?), string propagationPolicy = default(string), string dryRun = default(string), Dictionary<string, List<string>> customHeaders = null, CancellationToken cancellationToken = default(CancellationToken))
     {
-        if (group == null)
+        if (group is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "group");
         }
-        if (version == null)
+        if (version is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "version");
         }
-        if (namespaceParameter == null)
+        if (namespaceParameter is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "namespaceParameter");
         }
-        if (plural == null)
+        if (plural is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "plural");
         }
-        if (name == null)
+        if (name is null)
         {
             throw new ValidationException(ValidationRules.CannotBeNull, "name");
         }
@@ -630,19 +630,19 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         _url = _url.Replace("{plural}", System.Uri.EscapeDataString(plural));
         _url = _url.Replace("{name}", System.Uri.EscapeDataString(name));
         List<string> _queryParameters = new List<string>();
-        if (gracePeriodSeconds != null)
+        if (gracePeriodSeconds is not null)
         {
             _queryParameters.Add(string.Format("gracePeriodSeconds={0}", System.Uri.EscapeDataString(SafeJsonConvert.SerializeObject(gracePeriodSeconds, Client.SerializationSettings).Trim('"'))));
         }
-        if (orphanDependents != null)
+        if (orphanDependents is not null)
         {
             _queryParameters.Add(string.Format("orphanDependents={0}", System.Uri.EscapeDataString(SafeJsonConvert.SerializeObject(orphanDependents, Client.SerializationSettings).Trim('"'))));
         }
-        if (propagationPolicy != null)
+        if (propagationPolicy is not null)
         {
             _queryParameters.Add(string.Format("propagationPolicy={0}", System.Uri.EscapeDataString(propagationPolicy)));
         }
-        if (dryRun != null)
+        if (dryRun is not null)
         {
             _queryParameters.Add(string.Format("dryRun={0}", System.Uri.EscapeDataString(dryRun)));
         }
@@ -658,7 +658,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         // Set Headers
 
 
-        if (customHeaders != null)
+        if (customHeaders is not null)
         {
             foreach (var _header in customHeaders)
             {
@@ -672,14 +672,14 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
 
         // Serialize Request
         string _requestContent = null;
-        if (body != null)
+        if (body is not null)
         {
             _requestContent = SafeJsonConvert.SerializeObject(body, Client.SerializationSettings);
             _httpRequest.Content = new StringContent(_requestContent, System.Text.Encoding.UTF8);
             _httpRequest.Content.Headers.ContentType = Client.GetHeader(body);
         }
         // Set Credentials
-        if (Client.Credentials != null)
+        if (Client.Credentials is not null)
         {
             cancellationToken.ThrowIfCancellationRequested();
             await Client.Credentials.ProcessHttpRequestAsync(_httpRequest, cancellationToken).ConfigureAwait(false);
@@ -701,7 +701,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
         if ((int)_statusCode != 200)
         {
             var ex = new HttpOperationException(string.Format("Operation returned an invalid status code '{0}'", _statusCode));
-            if (_httpResponse.Content != null)
+            if (_httpResponse.Content is not null)
             {
                 _responseContent = await _httpResponse.Content.ReadAsStringAsync().ConfigureAwait(false);
             }
@@ -716,7 +716,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
                 ServiceClientTracing.Error(_invocationId, ex);
             }
             _httpRequest.Dispose();
-            if (_httpResponse != null)
+            if (_httpResponse is not null)
             {
                 _httpResponse.Dispose();
             }
@@ -737,7 +737,7 @@ public class AnyResourceKind : IServiceOperations<k8s.Kubernetes>, IAnyResourceK
             catch (JsonException ex)
             {
                 _httpRequest.Dispose();
-                if (_httpResponse != null)
+                if (_httpResponse is not null)
                 {
                     _httpResponse.Dispose();
                 }

src/OperatorFramework/src/Core/KubernetesCoreExtensions.cs

@@ -27,7 +27,7 @@ namespace Microsoft.Extensions.DependencyInjection
             {
                 services = services.Configure<KubernetesClientOptions>(options =>
                 {
-                    if (options.Configuration == null)
+                    if (options.Configuration is null)
                     {
                         options.Configuration = KubernetesClientConfiguration.BuildDefaultConfig();
                     }

src/OperatorFramework/src/Core/ResourceKinds/ResourceKindManager.cs

@@ -21,7 +21,7 @@ public class ResourceKindManager : IResourceKindManager
         foreach (var provider in _providers)
         {
             var resourceKind = await provider.GetResourceKindAsync(apiVersion, kind);
-            if (resourceKind != null)
+            if (resourceKind is not null)
             {
                 return resourceKind;
             }

src/OperatorFramework/src/Core/Resources/ResourcePatcher.cs

@@ -61,7 +61,7 @@ public class ResourcePatcher : IResourcePatcher
         {
             return ReplacePrimative(patch, context);
         }
-        else if (context.ApplyToken == null && context.LastAppliedToken != null)
+        else if (context.ApplyToken is null && context.LastAppliedToken is not null)
         {
             return patch.Remove(context.Path);
         }
@@ -105,7 +105,7 @@ public class ResourcePatcher : IResourcePatcher
         var lastApplied = context.LastAppliedToken as JObject;
         var live = context.LiveToken as JObject;
 
-        if (live == null)
+        if (live is null)
         {
             return patch.Replace(context.Path, apply);
         }
@@ -117,7 +117,7 @@ public class ResourcePatcher : IResourcePatcher
 
             var liveProperty = live.Property(name, StringComparison.Ordinal);
 
-            if (liveProperty == null)
+            if (liveProperty is null)
             {
                 patch = patch.Add(path, applyProperty.Value);
             }
@@ -141,10 +141,10 @@ public class ResourcePatcher : IResourcePatcher
             var name = liveProperty.Name;
             var applyProperty = apply.Property(name, StringComparison.Ordinal);
 
-            if (applyProperty == null)
+            if (applyProperty is null)
             {
                 var lastAppliedProperty = lastApplied?.Property(name, StringComparison.Ordinal);
-                if (lastAppliedProperty != null)
+                if (lastAppliedProperty is not null)
                 {
                     var path = $"{context.Path}/{EscapePath(name)}";
                     patch = patch.Remove(path);
@@ -161,7 +161,7 @@ public class ResourcePatcher : IResourcePatcher
         var lastApplied = context.LastAppliedToken as JObject;
         var live = context.LiveToken as JObject;
 
-        if (live == null)
+        if (live is null)
         {
             return patch.Replace(context.Path, apply);
         }
@@ -175,7 +175,7 @@ public class ResourcePatcher : IResourcePatcher
 
             var liveProperty = live.Property(key, StringComparison.Ordinal);
 
-            if (liveProperty == null)
+            if (liveProperty is null)
             {
                 patch = patch.Add(path, applyProperty.Value);
             }
@@ -199,10 +199,10 @@ public class ResourcePatcher : IResourcePatcher
             var name = liveProperty.Name;
             var applyProperty = apply.Property(name, StringComparison.Ordinal);
 
-            if (applyProperty == null)
+            if (applyProperty is null)
             {
                 var lastAppliedProperty = lastApplied?.Property(name, StringComparison.Ordinal);
-                if (lastAppliedProperty != null)
+                if (lastAppliedProperty is not null)
                 {
                     var path = $"{context.Path}/{EscapePath(name)}";
                     patch = patch.Remove(path);
@@ -321,7 +321,7 @@ public class ResourcePatcher : IResourcePatcher
             var (_, index, liveToken) = liveItems.SingleOrDefault(item => item.name == name);
             var (_, _, lastAppliedToken) = lastAppliedItems.SingleOrDefault(item => item.name == name);
 
-            if (liveToken != null)
+            if (liveToken is not null)
             {
                 var itemContext = context.Push(
                     path: $"{context.Path}/{index}",
@@ -343,7 +343,7 @@ public class ResourcePatcher : IResourcePatcher
             var (_, index, liveToken) = liveItems.SingleOrDefault(item => item.name == name);
             var (_, _, applyToken) = applyItems.SingleOrDefault(item => item.name == name);
 
-            if (applyToken == null && liveToken != null)
+            if (applyToken is null && liveToken is not null)
             {
                 patch = patch.Remove($"{context.Path}/{index}");
             }

src/OperatorFramework/src/CustomResource/CustomResourceDefinitionUpdater.cs

@@ -64,7 +64,7 @@ public class CustomResourceDefinitionUpdater<TResource> : IHostedService
 
         var existingCustomResourceDefinition = existingList?.Items?.SingleOrDefault();
 
-        if (existingCustomResourceDefinition != null)
+        if (existingCustomResourceDefinition is not null)
         {
             customResourceDefinition.Metadata.ResourceVersion = existingCustomResourceDefinition.ResourceVersion();
 

src/OperatorFramework/src/Operator/Caches/OperatorCacheWorkItem.cs

@@ -40,7 +40,7 @@ public struct OperatorCacheWorkItem<TResource> : IEquatable<OperatorCacheWorkIte
     /// <value>The related resources.</value>
     public ImmutableDictionary<GroupKindNamespacedName, IKubernetesObject<V1ObjectMeta>> Related { get; }
 
-    public bool IsEmpty => Resource == null && Related.IsEmpty;
+    public bool IsEmpty => Resource is null && Related.IsEmpty;
 
     /// <summary>
     /// Returns a WorkItem with Resource assigned to new value.

src/OperatorFramework/src/Operator/OperatorHandler.cs

@@ -220,7 +220,7 @@ public class OperatorHandler<TResource> : IOperatorHandler<TResource>
             };
         }
 
-        if (result.Error != null)
+        if (result.Error is not null)
         {
             // TODO: LOG Reconciler error
 

src/OperatorFramework/src/Operator/Reconcilers/OperatorReconciler.cs

@@ -91,7 +91,7 @@ public class OperatorReconciler<TResource> : IOperatorReconciler<TResource>
             throw new ArgumentNullException(nameof(parameters));
         }
 
-        if (parameters.Resource == null)
+        if (parameters.Resource is null)
         {
             // Custom resource has been deleted - k8s garbage collection will do the rest of the work
             return default;

src/OperatorFramework/src/ResourceKinds.OpenApi/OpenApiResourceKind.cs

@@ -106,14 +106,14 @@ public class OpenApiResourceKind : IResourceKind
     private static bool HasPatchStrategy(JsonSchema schema, string value)
     {
         return
-            schema.ExtensionData != null &&
+            schema.ExtensionData is not null &&
             schema.ExtensionData.TryGetValue("x-kubernetes-patch-strategy", out var patchStrategy) &&
             (patchStrategy as string ?? string.Empty).Split(',').Any(part => part == value);
     }
 
     private static bool HasPatchMergeKey(JsonSchema schema, out string mergeKey)
     {
-        if (schema.ExtensionData != null &&
+        if (schema.ExtensionData is not null &&
             schema.ExtensionData.TryGetValue("x-kubernetes-patch-merge-key", out var value) &&
             value is string stringValue)
         {

src/OperatorFramework/src/ResourceKinds.OpenApi/OpenApiResourceKindProvider.cs

@@ -60,7 +60,7 @@ public class OpenApiResourceKindProvider : IResourceKindProvider
     public async Task<IDictionary<string, JsonSchema>> LoadDefinitions()
     {
         using var stream = typeof(OpenApiResourceKindProvider).Assembly.GetManifestResourceStream(typeof(OpenApiResourceKindProvider), "swagger.json");
-        if (stream == null)
+        if (stream is null)
         {
             _logger.LogError(
                 new EventId(1, "MissingEmbeddedStream"),

src/OperatorFramework/test/UnitTests/Resources/ResourcePatcherTestsBase.cs

@@ -40,7 +40,7 @@ public abstract partial class ResourcePatcherTestsBase
             LiveResource = testYaml.Live,
         };
 
-        if (testYaml.ResourceKind != null)
+        if (testYaml.ResourceKind is not null)
         {
             parameters.ResourceKind = await Manager.GetResourceKindAsync(
                 testYaml.ResourceKind.ApiVersion,
@@ -66,7 +66,7 @@ public abstract partial class ResourcePatcherTestsBase
             LiveResource = testYaml.Live,
         };
 
-        if (testYaml.ResourceKind != null)
+        if (testYaml.ResourceKind is not null)
         {
             parameters.ResourceKind = await Manager.GetResourceKindAsync(
                 testYaml.ResourceKind.ApiVersion,

src/OperatorFramework/test/UnitTests/Utils/TestYaml.cs

@@ -42,7 +42,7 @@ public static class TestYaml
         }
 
         var manifestStream = reflectedType.Assembly.GetManifestResourceStream(reflectedType, $"{reflectedType.Name}.{methodName}.yaml");
-        if (manifestStream == null)
+        if (manifestStream is null)
         {
             throw new FileNotFoundException($"Could not find embedded stream {reflectedType.FullName}.{methodName}.yaml");
         }

src/ReverseProxy/Configuration/ActiveHealthCheckConfig.cs

@@ -37,7 +37,7 @@ public sealed record ActiveHealthCheckConfig
 
     public bool Equals(ActiveHealthCheckConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/ClusterConfig.cs

@@ -56,7 +56,7 @@ public sealed record ClusterConfig
 
     public bool Equals(ClusterConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }
@@ -67,7 +67,7 @@ public sealed record ClusterConfig
 
     internal bool EqualsExcludingDestinations(ClusterConfig other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/ConfigProvider/ConfigurationConfigProvider.cs

@@ -52,7 +52,7 @@ internal sealed class ConfigurationConfigProvider : IProxyConfigProvider, IDispo
     public IProxyConfig GetConfig()
     {
         // First time load
-        if (_snapshot == null)
+        if (_snapshot is null)
         {
             _subscription = ChangeToken.OnChange(_configuration.GetReloadToken, UpdateSnapshot);
             UpdateSnapshot();
@@ -88,7 +88,7 @@ internal sealed class ConfigurationConfigProvider : IProxyConfigProvider, IDispo
                 Log.ConfigurationDataConversionFailed(_logger, ex);
 
                 // Re-throw on the first time load to prevent app from starting.
-                if (_snapshot == null)
+                if (_snapshot is null)
                 {
                     throw;
                 }
@@ -319,7 +319,7 @@ internal sealed class ConfigurationConfigProvider : IProxyConfigProvider, IDispo
         {
             foreach (var protocolConfig in sslProtocolsSection.GetChildren().Select(s => Enum.Parse<SslProtocols>(s.Value, ignoreCase: true)))
             {
-                sslProtocols = sslProtocols == null ? protocolConfig : sslProtocols | protocolConfig;
+                sslProtocols = sslProtocols is null ? protocolConfig : sslProtocols | protocolConfig;
             }
         }
 

src/ReverseProxy/Configuration/ConfigValidator.cs

@@ -70,13 +70,13 @@ internal sealed class ConfigValidator : IConfigValidator
         await ValidateAuthorizationPolicyAsync(errors, route.AuthorizationPolicy, route.RouteId);
         await ValidateCorsPolicyAsync(errors, route.CorsPolicy, route.RouteId);
 
-        if (route.Match == null)
+        if (route.Match is null)
         {
             errors.Add(new ArgumentException($"Route '{route.RouteId}' did not set any match criteria, it requires Hosts or Path specified. Set the Path to '/{{**catchall}}' to match all requests."));
             return errors;
         }
 
-        if ((route.Match.Hosts == null || !route.Match.Hosts.Any(host => !string.IsNullOrEmpty(host))) && string.IsNullOrEmpty(route.Match.Path))
+        if ((route.Match.Hosts is null || !route.Match.Hosts.Any(host => !string.IsNullOrEmpty(host))) && string.IsNullOrEmpty(route.Match.Path))
         {
             errors.Add(new ArgumentException($"Route '{route.RouteId}' requires Hosts or Path specified. Set the Path to '/{{**catchall}}' to match all requests."));
         }
@@ -114,7 +114,7 @@ internal sealed class ConfigValidator : IConfigValidator
     private static void ValidateHost(IList<Exception> errors, IReadOnlyList<string>? hosts, string routeId)
     {
         // Host is optional when Path is specified
-        if (hosts == null || hosts.Count == 0)
+        if (hosts is null || hosts.Count == 0)
         {
             return;
         }
@@ -153,7 +153,7 @@ internal sealed class ConfigValidator : IConfigValidator
     private static void ValidateMethods(IList<Exception> errors, IReadOnlyList<string>? methods, string routeId)
     {
         // Methods are optional
-        if (methods == null)
+        if (methods is null)
         {
             return;
         }
@@ -177,14 +177,14 @@ internal sealed class ConfigValidator : IConfigValidator
     private static void ValidateHeaders(List<Exception> errors, IReadOnlyList<RouteHeader>? headers, string routeId)
     {
         // Headers are optional
-        if (headers == null)
+        if (headers is null)
         {
             return;
         }
 
         foreach (var header in headers)
         {
-            if (header == null)
+            if (header is null)
             {
                 errors.Add(new ArgumentException($"A null route header has been set for route '{routeId}'."));
                 continue;
@@ -196,7 +196,7 @@ internal sealed class ConfigValidator : IConfigValidator
             }
 
             if (header.Mode != HeaderMatchMode.Exists
-                && (header.Values == null || header.Values.Count == 0))
+                && (header.Values is null || header.Values.Count == 0))
             {
                 errors.Add(new ArgumentException($"No header values were set on route header '{header.Name}' for route '{routeId}'."));
             }
@@ -211,14 +211,14 @@ internal sealed class ConfigValidator : IConfigValidator
     private static void ValidateQueryParameters(List<Exception> errors, IReadOnlyList<RouteQueryParameter>? queryparams, string routeId)
     {
         // Query Parameters are optional
-        if (queryparams == null)
+        if (queryparams is null)
         {
             return;
         }
 
         foreach (var queryparam in queryparams)
         {
-            if (queryparam == null)
+            if (queryparam is null)
             {
                 errors.Add(new ArgumentException($"A null route query parameter has been set for route '{routeId}'."));
                 continue;
@@ -230,7 +230,7 @@ internal sealed class ConfigValidator : IConfigValidator
             }
 
             if (queryparam.Mode != QueryParameterMatchMode.Exists
-                && (queryparam.Values == null || queryparam.Values.Count == 0))
+                && (queryparam.Values is null || queryparam.Values.Count == 0))
             {
                 errors.Add(new ArgumentException($"No query parameter values were set on route query parameter '{queryparam.Name}' for route '{routeId}'."));
             }
@@ -252,7 +252,7 @@ internal sealed class ConfigValidator : IConfigValidator
         if (string.Equals(AuthorizationConstants.Default, authorizationPolicyName, StringComparison.OrdinalIgnoreCase))
         {
             var policy = await _authorizationPolicyProvider.GetPolicyAsync(authorizationPolicyName);
-            if (policy != null)
+            if (policy is not null)
             {
                 errors.Add(new ArgumentException($"The application has registered an authorization policy named '{authorizationPolicyName}' that conflicts with the reserved authorization policy name used on this route. The registered policy name needs to be changed for this route to function."));
             }
@@ -262,7 +262,7 @@ internal sealed class ConfigValidator : IConfigValidator
         if (string.Equals(AuthorizationConstants.Anonymous, authorizationPolicyName, StringComparison.OrdinalIgnoreCase))
         {
             var policy = await _authorizationPolicyProvider.GetPolicyAsync(authorizationPolicyName);
-            if (policy != null)
+            if (policy is not null)
             {
                 errors.Add(new ArgumentException($"The application has registered an authorization policy named '{authorizationPolicyName}' that conflicts with the reserved authorization policy name used on this route. The registered policy name needs to be changed for this route to function."));
             }
@@ -272,7 +272,7 @@ internal sealed class ConfigValidator : IConfigValidator
         try
         {
             var policy = await _authorizationPolicyProvider.GetPolicyAsync(authorizationPolicyName);
-            if (policy == null)
+            if (policy is null)
             {
                 errors.Add(new ArgumentException($"Authorization policy '{authorizationPolicyName}' not found for route '{routeId}'."));
             }
@@ -294,7 +294,7 @@ internal sealed class ConfigValidator : IConfigValidator
         {
             var dummyHttpContext = new DefaultHttpContext();
             var policy = await _corsPolicyProvider.GetPolicyAsync(dummyHttpContext, corsPolicyName);
-            if (policy != null)
+            if (policy is not null)
             {
                 errors.Add(new ArgumentException($"The application has registered a CORS policy named '{corsPolicyName}' that conflicts with the reserved CORS policy name used on this route. The registered policy name needs to be changed for this route to function."));
             }
@@ -305,7 +305,7 @@ internal sealed class ConfigValidator : IConfigValidator
         {
             var dummyHttpContext = new DefaultHttpContext();
             var policy = await _corsPolicyProvider.GetPolicyAsync(dummyHttpContext, corsPolicyName);
-            if (policy != null)
+            if (policy is not null)
             {
                 errors.Add(new ArgumentException($"The application has registered a CORS policy named '{corsPolicyName}' that conflicts with the reserved CORS policy name used on this route. The registered policy name needs to be changed for this route to function."));
             }
@@ -316,7 +316,7 @@ internal sealed class ConfigValidator : IConfigValidator
         {
             var dummyHttpContext = new DefaultHttpContext();
             var policy = await _corsPolicyProvider.GetPolicyAsync(dummyHttpContext, corsPolicyName);
-            if (policy == null)
+            if (policy is null)
             {
                 errors.Add(new ArgumentException($"CORS policy '{corsPolicyName}' not found for route '{routeId}'."));
             }
@@ -371,17 +371,17 @@ internal sealed class ConfigValidator : IConfigValidator
 
         var cookieConfig = cluster.SessionAffinity.Cookie;
 
-        if (cookieConfig == null)
+        if (cookieConfig is null)
         {
             return;
         }
 
-        if (cookieConfig.Expiration != null && cookieConfig.Expiration <= TimeSpan.Zero)
+        if (cookieConfig.Expiration is not null && cookieConfig.Expiration <= TimeSpan.Zero)
         {
             errors.Add(new ArgumentException($"Session affinity cookie expiration must be positive or null."));
         }
 
-        if (cookieConfig.MaxAge != null && cookieConfig.MaxAge <= TimeSpan.Zero)
+        if (cookieConfig.MaxAge is not null && cookieConfig.MaxAge <= TimeSpan.Zero)
         {
             errors.Add(new ArgumentException($"Session affinity cookie max-age must be positive or null."));
         }
@@ -389,19 +389,19 @@ internal sealed class ConfigValidator : IConfigValidator
 
     private static void ValidateProxyHttpClient(IList<Exception> errors, ClusterConfig cluster)
     {
-        if (cluster.HttpClient == null)
+        if (cluster.HttpClient is null)
         {
             // Proxy http client options are not set.
             return;
         }
 
-        if (cluster.HttpClient.MaxConnectionsPerServer != null && cluster.HttpClient.MaxConnectionsPerServer <= 0)
+        if (cluster.HttpClient.MaxConnectionsPerServer is not null && cluster.HttpClient.MaxConnectionsPerServer <= 0)
         {
             errors.Add(new ArgumentException($"Max connections per server limit set on the cluster '{cluster.ClusterId}' must be positive."));
         }
 #if NET
         var encoding = cluster.HttpClient.RequestHeaderEncoding;
-        if (encoding != null)
+        if (encoding is not null)
         {
             try
             {
@@ -417,13 +417,13 @@ internal sealed class ConfigValidator : IConfigValidator
 
     private static void ValidateProxyHttpRequest(IList<Exception> errors, ClusterConfig cluster)
     {
-        if (cluster.HttpRequest == null)
+        if (cluster.HttpRequest is null)
         {
             // Proxy http request options are not set.
             return;
         }
 
-        if (cluster.HttpRequest.Version != null &&
+        if (cluster.HttpRequest.Version is not null &&
             cluster.HttpRequest.Version != HttpVersion.Version10 &&
             cluster.HttpRequest.Version != HttpVersion.Version11 &&
             cluster.HttpRequest.Version != HttpVersion.Version20)
@@ -470,12 +470,12 @@ internal sealed class ConfigValidator : IConfigValidator
             errors.Add(new ArgumentException($"No matching {nameof(IActiveHealthCheckPolicy)} found for the active health check policy name '{policy}' set on the cluster '{cluster.ClusterId}'."));
         }
 
-        if (activeOptions.Interval != null && activeOptions.Interval <= TimeSpan.Zero)
+        if (activeOptions.Interval is not null && activeOptions.Interval <= TimeSpan.Zero)
         {
             errors.Add(new ArgumentException($"Destination probing interval set on the cluster '{cluster.ClusterId}' must be positive."));
         }
 
-        if (activeOptions.Timeout != null && activeOptions.Timeout <= TimeSpan.Zero)
+        if (activeOptions.Timeout is not null && activeOptions.Timeout <= TimeSpan.Zero)
         {
             errors.Add(new ArgumentException($"Destination probing timeout set on the cluster '{cluster.ClusterId}' must be positive."));
         }
@@ -501,7 +501,7 @@ internal sealed class ConfigValidator : IConfigValidator
             errors.Add(new ArgumentException($"No matching {nameof(IPassiveHealthCheckPolicy)} found for the passive health check policy name '{policy}' set on the cluster '{cluster.ClusterId}'."));
         }
 
-        if (passiveOptions.ReactivationPeriod != null && passiveOptions.ReactivationPeriod <= TimeSpan.Zero)
+        if (passiveOptions.ReactivationPeriod is not null && passiveOptions.ReactivationPeriod <= TimeSpan.Zero)
         {
             errors.Add(new ArgumentException($"Unhealthy destination reactivation period set on the cluster '{cluster.ClusterId}' must be positive."));
         }

src/ReverseProxy/Configuration/DestinationConfig.cs

@@ -30,7 +30,7 @@ public sealed record DestinationConfig
 
     public bool Equals(DestinationConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/HealthCheckConfig.cs

@@ -27,7 +27,7 @@ public sealed record HealthCheckConfig
 
     public bool Equals(HealthCheckConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/HttpClientConfig.cs

@@ -53,7 +53,7 @@ public sealed record HttpClientConfig
 
     public bool Equals(HttpClientConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/PassiveHealthCheckConfig.cs

@@ -27,7 +27,7 @@ public sealed record PassiveHealthCheckConfig
 
     public bool Equals(PassiveHealthCheckConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/RouteConfig.cs

@@ -64,7 +64,7 @@ public sealed record RouteConfig
 
     public bool Equals(RouteConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/RouteHeader.cs

@@ -40,7 +40,7 @@ public sealed record RouteHeader
 
     public bool Equals(RouteHeader? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/RouteMatch.cs

@@ -40,7 +40,7 @@ public sealed record RouteMatch
 
     public bool Equals(RouteMatch? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/RouteQueryParameter.cs

@@ -39,7 +39,7 @@ public sealed record RouteQueryParameter
 
     public bool Equals(RouteQueryParameter? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/SessionAffinityConfig.cs

@@ -45,7 +45,7 @@ public sealed record SessionAffinityConfig
 
     public bool Equals(SessionAffinityConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/SessionAffinityCookieConfig.cs

@@ -60,7 +60,7 @@ public sealed record SessionAffinityCookieConfig
 
     public bool Equals(SessionAffinityCookieConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Configuration/WebProxyConfig.cs

@@ -29,7 +29,7 @@ public sealed record WebProxyConfig : IEquatable<WebProxyConfig>
 
     public bool Equals(WebProxyConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Delegation/DelegationExtensions.cs

@@ -19,7 +19,7 @@ internal static class DelegationExtensions
 
     public static bool ShouldUseHttpSysDelegation(this DestinationState destination)
     {
-        return destination.GetHttpSysDelegationQueue() != null;
+        return destination.GetHttpSysDelegationQueue() is not null;
     }
 }
 #endif

src/ReverseProxy/Delegation/HttpSysDelegator.cs

@@ -52,7 +52,7 @@ internal sealed class HttpSysDelegator : IClusterChangeListener
                 "Current request can't be delegated. Either the request body has started to be read or the response has started to be sent.");
         }
 
-        if (_delegationFeature == null || !_queuesPerDestination.TryGetValue(destination, out var queue))
+        if (_delegationFeature is null || !_queuesPerDestination.TryGetValue(destination, out var queue))
         {
             Log.QueueNotFound(_logger, destination);
             context.Response.StatusCode = StatusCodes.Status503ServiceUnavailable;
@@ -102,7 +102,7 @@ internal sealed class HttpSysDelegator : IClusterChangeListener
 
     private void AddOrUpdateRules(ClusterState cluster)
     {
-        if (_delegationFeature == null)
+        if (_delegationFeature is null)
         {
             return;
         }
@@ -121,7 +121,7 @@ internal sealed class HttpSysDelegator : IClusterChangeListener
         {
             var queueName = destination.GetHttpSysDelegationQueue();
             var urlPrefix = destination.Model?.Config?.Address;
-            if (queueName != null && urlPrefix != null)
+            if (queueName is not null && urlPrefix is not null)
             {
                 var queueKey = new QueueKey(queueName, urlPrefix);
                 if (!_queuesPerDestination.TryGetValue(destination, out var queue) || !queue.Equals(queueKey))
@@ -140,7 +140,7 @@ internal sealed class HttpSysDelegator : IClusterChangeListener
                         queueWeakRef.TryGetTarget(out queue);
                     }
 
-                    if (queue != null)
+                    if (queue is not null)
                     {
                         // We call this outside of the above if bock so that if previous
                         // initialization failed, we will retry it for every new destination added.

src/ReverseProxy/Forwarder/ForwarderHttpClientFactory.cs

@@ -69,7 +69,7 @@ public class ForwarderHttpClientFactory : IForwarderHttpClientFactory
     /// </summary>
     protected virtual bool CanReuseOldClient(ForwarderHttpClientContext context)
     {
-        return context.OldClient != null && context.NewConfig == context.OldConfig;
+        return context.OldClient is not null && context.NewConfig == context.OldConfig;
     }
 
     /// <summary>
@@ -86,7 +86,7 @@ public class ForwarderHttpClientFactory : IForwarderHttpClientFactory
         {
             handler.SslOptions.EnabledSslProtocols = newConfig.SslProtocols.Value;
         }
-        if (newConfig.MaxConnectionsPerServer != null)
+        if (newConfig.MaxConnectionsPerServer is not null)
         {
             handler.MaxConnectionsPerServer = newConfig.MaxConnectionsPerServer.Value;
         }
@@ -97,14 +97,14 @@ public class ForwarderHttpClientFactory : IForwarderHttpClientFactory
 #if NET
         handler.EnableMultipleHttp2Connections = newConfig.EnableMultipleHttp2Connections.GetValueOrDefault(true);
 
-        if (newConfig.RequestHeaderEncoding != null)
+        if (newConfig.RequestHeaderEncoding is not null)
         {
             var encoding = Encoding.GetEncoding(newConfig.RequestHeaderEncoding);
             handler.RequestHeaderEncodingSelector = (_, _) => encoding;
         }
 #endif
         var webProxy = TryCreateWebProxy(newConfig.WebProxy);
-        if (webProxy != null)
+        if (webProxy is not null)
         {
             handler.Proxy = webProxy;
             handler.UseProxy = true;
@@ -113,7 +113,7 @@ public class ForwarderHttpClientFactory : IForwarderHttpClientFactory
 
     private static IWebProxy? TryCreateWebProxy(WebProxyConfig? webProxyConfig)
     {
-        if (webProxyConfig == null || webProxyConfig.Address == null)
+        if (webProxyConfig is null || webProxyConfig.Address is null)
         {
             return null;
         }

src/ReverseProxy/Forwarder/ForwarderMiddleware.cs

@@ -59,7 +59,7 @@ internal sealed class ForwarderMiddleware
         reverseProxyFeature.ProxiedDestination = destination;
 
         var destinationModel = destination.Model;
-        if (destinationModel == null)
+        if (destinationModel is null)
         {
             throw new InvalidOperationException($"Chosen destination has no model set: '{destination.DestinationId}'");
         }

src/ReverseProxy/Forwarder/ForwarderRequestConfig.cs

@@ -47,7 +47,7 @@ public sealed record ForwarderRequestConfig
 
     public bool Equals(ForwarderRequestConfig? other)
     {
-        if (other == null)
+        if (other is null)
         {
             return false;
         }

src/ReverseProxy/Forwarder/HttpForwarder.cs

@@ -257,7 +257,7 @@ internal sealed class HttpForwarder : IHttpForwarder
         HttpTransformer transformer, ForwarderRequestConfig? requestConfig, bool isStreamingRequest, ActivityCancellationTokenSource activityToken)
     {
         // "http://a".Length = 8
-        if (destinationPrefix == null || destinationPrefix.Length < 8)
+        if (destinationPrefix is null || destinationPrefix.Length < 8)
         {
             throw new ArgumentException("Invalid destination prefix.", nameof(destinationPrefix));
         }
@@ -325,7 +325,7 @@ internal sealed class HttpForwarder : IHttpForwarder
             }
         }
 
-        if (connectionUpgradeValue != null && context.Request.Headers.TryGetValue(HeaderNames.Upgrade, out var upgradeValue))
+        if (connectionUpgradeValue is not null && context.Request.Headers.TryGetValue(HeaderNames.Upgrade, out var upgradeValue))
         {
             request.Headers.TryAddWithoutValidation(HeaderNames.Connection, connectionUpgradeValue);
             request.Headers.TryAddWithoutValidation(HeaderNames.Upgrade, (IEnumerable<string>)upgradeValue);
@@ -344,7 +344,7 @@ internal sealed class HttpForwarder : IHttpForwarder
 
 #if NET
         var canHaveBodyFeature = request.HttpContext.Features.Get<IHttpRequestBodyDetectionFeature>();
-        if (canHaveBodyFeature != null)
+        if (canHaveBodyFeature is not null)
         {
             // 5.0 servers provide a definitive answer for us.
             hasBody = canHaveBodyFeature.CanHaveBody;
@@ -548,14 +548,14 @@ internal sealed class HttpForwarder : IHttpForwarder
         // SocketHttpHandler and similar transports always provide an HttpContent object, even if it's empty.
         // Note as of 5.0 HttpResponse.Content never returns null.
         // https://github.com/dotnet/runtime/blame/8fc68f626a11d646109a758cb0fc70a0aa7826f1/src/libraries/System.Net.Http/src/System/Net/Http/HttpResponseMessage.cs#L46
-        if (destinationResponse.Content == null)
+        if (destinationResponse.Content is null)
         {
             throw new InvalidOperationException("A response content is required for upgrades.");
         }
 
         // :: Step 7-A-1: Upgrade the client channel. This will also send response headers.
         var upgradeFeature = context.Features.Get<IHttpUpgradeFeature>();
-        if (upgradeFeature == null)
+        if (upgradeFeature is null)
         {
             var ex = new InvalidOperationException("Invalid 101 response when upgrades aren't supported.");
             destinationResponse.Dispose();
@@ -637,7 +637,7 @@ internal sealed class HttpForwarder : IHttpForwarder
         // In 3.1 this is only likely to return null in tests.
         // As of 5.0 HttpResponse.Content never returns null.
         // https://github.com/dotnet/runtime/blame/8fc68f626a11d646109a758cb0fc70a0aa7826f1/src/libraries/System.Net.Http/src/System/Net/Http/HttpResponseMessage.cs#L46
-        if (destinationResponseContent != null)
+        if (destinationResponseContent is not null)
         {
             using var destinationResponseStream = await destinationResponseContent.ReadAsStreamAsync();
             // The response content-length is enforced by the server.
@@ -711,13 +711,13 @@ internal sealed class HttpForwarder : IHttpForwarder
     private void DisableMinRequestBodyDataRateAndMaxRequestBodySize(HttpContext httpContext)
     {
         var minRequestBodyDataRateFeature = httpContext.Features.Get<IHttpMinRequestBodyDataRateFeature>();
-        if (minRequestBodyDataRateFeature != null)
+        if (minRequestBodyDataRateFeature is not null)
         {
             minRequestBodyDataRateFeature.MinDataRate = null;
         }
 
         var maxRequestBodySizeFeature = httpContext.Features.Get<IHttpMaxRequestBodySizeFeature>();
-        if (maxRequestBodySizeFeature != null)
+        if (maxRequestBodySizeFeature is not null)
         {
             if (!maxRequestBodySizeFeature.IsReadOnly)
             {
@@ -742,7 +742,7 @@ internal sealed class HttpForwarder : IHttpForwarder
     private static void ResetOrAbort(HttpContext context, bool isCancelled)
     {
         var resetFeature = context.Features.Get<IHttpResetFeature>();
-        if (resetFeature != null)
+        if (resetFeature is not null)
         {
             // https://tools.ietf.org/html/rfc7540#section-7
             const int Cancelled = 2;

src/ReverseProxy/Forwarder/HttpTransformer.cs

@@ -79,7 +79,7 @@ public class HttpTransformer
         if (ProtocolHelper.IsHttp2OrGreater(httpContext.Request.Protocol))
         {
             var te = httpContext.Request.Headers.GetCommaSeparatedValues(HeaderNames.TE);
-            if (te != null)
+            if (te is not null)
             {
                 for (var i = 0; i < te.Length; i++)
                 {
@@ -109,14 +109,14 @@ public class HttpTransformer
     /// etc.</returns>
     public virtual ValueTask<bool> TransformResponseAsync(HttpContext httpContext, HttpResponseMessage? proxyResponse)
     {
-        if (proxyResponse == null)
+        if (proxyResponse is null)
         {
             return new ValueTask<bool>(false);
         }
 
         var responseHeaders = httpContext.Response.Headers;
         CopyResponseHeaders(proxyResponse.Headers, responseHeaders);
-        if (proxyResponse.Content != null)
+        if (proxyResponse.Content is not null)
         {
             CopyResponseHeaders(proxyResponse.Content.Headers, responseHeaders);
         }
@@ -129,7 +129,7 @@ public class HttpTransformer
         // (Section 9.4) and ought to be handled as an error.  A sender MUST
         // remove the received Content-Length field prior to forwarding such
         // a message downstream.
-        if (proxyResponse.Content != null
+        if (proxyResponse.Content is not null
             && RequestUtilities.ContainsHeader(proxyResponse.Headers, HeaderNames.TransferEncoding)
             && RequestUtilities.ContainsHeader(proxyResponse.Content.Headers, HeaderNames.ContentLength))
         {
@@ -151,7 +151,7 @@ public class HttpTransformer
         // because they lookup `IHttpResponseTrailersFeature` for every call. Here we do it just once instead.
         var responseTrailersFeature = httpContext.Features.Get<IHttpResponseTrailersFeature>();
         var outgoingTrailers = responseTrailersFeature?.Trailers;
-        if (outgoingTrailers != null && !outgoingTrailers.IsReadOnly)
+        if (outgoingTrailers is not null && !outgoingTrailers.IsReadOnly)
         {
             // Note that trailers, if any, should already have been declared in Proxy's response
             // by virtue of us having proxied all response headers in step 6.

src/ReverseProxy/Forwarder/ProtocolHelper.cs

@@ -49,7 +49,7 @@ internal static class ProtocolHelper
 #if NET
         return HttpProtocol.GetHttpProtocol(version);
 #else
-        if (version == null)
+        if (version is null)
         {
             throw new ArgumentNullException(nameof(version));
         }
@@ -86,7 +86,7 @@ internal static class ProtocolHelper
     /// </summary>
     public static bool IsGrpcContentType(string? contentType)
     {
-        if (contentType == null)
+        if (contentType is null)
         {
             return false;
         }

src/ReverseProxy/Health/ActiveHealthCheckMonitor.cs

@@ -71,7 +71,7 @@ internal partial class ActiveHealthCheckMonitor : IActiveHealthCheckMonitor, ICl
     public void OnClusterAdded(ClusterState cluster)
     {
         var config = cluster.Model.Config.HealthCheck?.Active;
-        if (config != null && config.Enabled.GetValueOrDefault())
+        if (config is not null && config.Enabled.GetValueOrDefault())
         {
             Scheduler.ScheduleEntity(cluster, config.Interval ?? _monitorOptions.DefaultInterval);
         }
@@ -80,7 +80,7 @@ internal partial class ActiveHealthCheckMonitor : IActiveHealthCheckMonitor, ICl
     public void OnClusterChanged(ClusterState cluster)
     {
         var config = cluster.Model.Config.HealthCheck?.Active;
-        if (config != null && config.Enabled.GetValueOrDefault())
+        if (config is not null && config.Enabled.GetValueOrDefault())
         {
             Scheduler.ChangePeriod(cluster, config.Interval ?? _monitorOptions.DefaultInterval);
         }
@@ -103,7 +103,7 @@ internal partial class ActiveHealthCheckMonitor : IActiveHealthCheckMonitor, ICl
     private async Task ProbeCluster(ClusterState cluster)
     {
         var config = cluster.Model.Config.HealthCheck?.Active;
-        if (config == null || !config.Enabled.GetValueOrDefault())
+        if (config is null || !config.Enabled.GetValueOrDefault())
         {
             return;
         }

src/ReverseProxy/Health/ClusterDestinationsUpdater.cs

@@ -23,7 +23,7 @@ internal sealed class ClusterDestinationsUpdater : IClusterDestinationsUpdater
     public void UpdateAvailableDestinations(ClusterState cluster)
     {
         var allDestinations = cluster.DestinationsState?.AllDestinations;
-        if (allDestinations == null)
+        if (allDestinations is null)
         {
             throw new InvalidOperationException($"{nameof(UpdateAllDestinations)} must be called first.");
         }

src/ReverseProxy/Health/ConsecutiveFailuresHealthPolicy.cs

@@ -58,7 +58,7 @@ internal sealed class ConsecutiveFailuresHealthPolicy : IActiveHealthCheckPolicy
     private static DestinationHealth EvaluateHealthState(double threshold, HttpResponseMessage? response, AtomicCounter count)
     {
         DestinationHealth newHealth;
-        if (response != null && response.IsSuccessStatusCode)
+        if (response is not null && response.IsSuccessStatusCode)
         {
             // Success
             count.Reset();

src/ReverseProxy/Health/PassiveHealthCheckMiddleware.cs

@@ -28,7 +28,7 @@ public class PassiveHealthCheckMiddleware
         var options = proxyFeature.Cluster.Config.HealthCheck?.Passive;
 
         // Do nothing if no target destination has been chosen for the request.
-        if (options == null || !options.Enabled.GetValueOrDefault() || proxyFeature.ProxiedDestination == null)
+        if (options is null || !options.Enabled.GetValueOrDefault() || proxyFeature.ProxiedDestination is null)
         {
             return;
         }

src/ReverseProxy/Health/TransportFailureRateHealthPolicy.cs

@@ -47,7 +47,7 @@ internal sealed class TransportFailureRateHealthPolicy : IPassiveHealthCheckPoli
     public void RequestProxied(HttpContext context, ClusterState cluster, DestinationState destination)
     {
         var error = context.Features.Get<IForwarderErrorFeature>();
-        var newHealth = EvaluateProxiedRequest(cluster, destination, error != null);
+        var newHealth = EvaluateProxiedRequest(cluster, destination, error is not null);
         var clusterReactivationPeriod = cluster.Model.Config.HealthCheck?.Passive?.ReactivationPeriod ?? _defaultReactivationPeriod;
         // Avoid reactivating until the history has expired so that it does not affect future health assessments.
         var reactivationPeriod = clusterReactivationPeriod >= _policyOptions.DetectionWindowSize ? clusterReactivationPeriod : _policyOptions.DetectionWindowSize;

src/ReverseProxy/LoadBalancing/LoadBalancingMiddleware.cs

@@ -53,7 +53,7 @@ internal sealed class LoadBalancingMiddleware
             destination = currentPolicy.PickDestination(context, proxyFeature.Route.Cluster!, destinations);
         }
 
-        if (destination == null)
+        if (destination is null)
         {
             // We intentionally do not short circuit here, we allow for later middleware to decide how to handle this case.
             Log.NoAvailableDestinations(_logger, proxyFeature.Cluster.Config.ClusterId);

src/ReverseProxy/Management/ProxyConfigManager.cs

@@ -104,11 +104,11 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
         {
             // The Endpoints needs to be lazy the first time to give a chance to ReverseProxyConventionBuilder to add its conventions.
             // Endpoints are accessed by routing on the first request.
-            if (_endpoints == null)
+            if (_endpoints is null)
             {
                 lock (_syncRoot)
                 {
-                    if (_endpoints == null)
+                    if (_endpoints is null)
                     {
                         CreateEndpoints();
                     }
@@ -127,7 +127,7 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
         {
             // Only rebuild the endpoint for modified routes or clusters.
             var endpoint = existingRoute.Value.CachedEndpoint;
-            if (endpoint == null)
+            if (endpoint is null)
             {
                 endpoint = _proxyEndpointFactory.CreateEndpoint(existingRoute.Value.Model, _conventions);
                 existingRoute.Value.CachedEndpoint = endpoint;
@@ -216,7 +216,7 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
                 {
                     // Skip if changes are signaled before the endpoints are initialized for the first time.
                     // The endpoint conventions might not be ready yet.
-                    if (hasChanged && _endpoints != null)
+                    if (hasChanged && _endpoints is not null)
                     {
                         CreateEndpoints();
                     }
@@ -233,11 +233,11 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
 
     private static void ValidateConfigProperties(IProxyConfig config)
     {
-        if (config == null)
+        if (config is null)
         {
             throw new InvalidOperationException($"{nameof(IProxyConfigProvider.GetConfig)} returned a null value.");
         }
-        if (config.ChangeToken == null)
+        if (config.ChangeToken is null)
         {
             throw new InvalidOperationException($"{nameof(IProxyConfig.ChangeToken)} has a null value.");
         }
@@ -316,7 +316,7 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
 
     private async Task<(IList<RouteConfig>, IList<Exception>)> VerifyRoutesAsync(IReadOnlyList<RouteConfig> routes, IReadOnlyDictionary<string, ClusterConfig> clusters, CancellationToken cancellation)
     {
-        if (routes == null)
+        if (routes is null)
         {
             return (Array.Empty<RouteConfig>(), Array.Empty<Exception>());
         }
@@ -340,7 +340,7 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
                 if (_filters.Length != 0)
                 {
                     ClusterConfig? cluster = null;
-                    if (route.ClusterId != null)
+                    if (route.ClusterId is not null)
                     {
                         clusters.TryGetValue(route.ClusterId, out cluster);
                     }
@@ -377,7 +377,7 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
 
     private async Task<(IReadOnlyDictionary<string, ClusterConfig>, IList<Exception>)> VerifyClustersAsync(IReadOnlyList<ClusterConfig> clusters, CancellationToken cancellation)
     {
-        if (clusters == null)
+        if (clusters is null)
         {
             return (_emptyClusterDictionary, Array.Empty<Exception>());
         }
@@ -530,7 +530,7 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
         var desiredDestinations = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
         var changed = false;
 
-        if (incomingDestinations != null)
+        if (incomingDestinations is not null)
         {
             foreach (var incomingDestination in incomingDestinations)
             {
@@ -649,7 +649,7 @@ internal sealed class ProxyConfigManager : EndpointDataSource, IProxyStateLookup
     [MemberNotNull(nameof(_endpoints))]
     private void UpdateEndpoints(List<Endpoint> endpoints)
     {
-        if (endpoints == null)
+        if (endpoints is null)
         {
             throw new ArgumentNullException(nameof(endpoints));
         }

src/ReverseProxy/Model/ProxyPipelineInitializerMiddleware.cs

@@ -33,7 +33,7 @@ internal sealed class ProxyPipelineInitializerMiddleware
 
         var cluster = route.Cluster;
         // TODO: Validate on load https://github.com/microsoft/reverse-proxy/issues/797
-        if (cluster == null)
+        if (cluster is null)
         {
             Log.NoClusterFound(_logger, route.Config.RouteId);
             context.Response.StatusCode = StatusCodes.Status503ServiceUnavailable;

src/ReverseProxy/Routing/HeaderMatcher.cs

@@ -22,7 +22,7 @@ internal sealed class HeaderMatcher
             throw new ArgumentException("A header name is required.", nameof(name));
         }
         if (mode != HeaderMatchMode.Exists
-            && (values == null || values.Count == 0))
+            && (values is null || values.Count == 0))
         {
             throw new ArgumentException("Header values must have at least one value.", nameof(values));
         }

src/ReverseProxy/Routing/HeaderMatcherPolicy.cs

@@ -60,7 +60,7 @@ internal sealed class HeaderMatcherPolicy : MatcherPolicy, IEndpointComparerPoli
 
             var matchers = candidates[i].Endpoint.Metadata.GetMetadata<IHeaderMetadata>()?.Matchers;
 
-            if (matchers == null)
+            if (matchers is null)
             {
                 continue;
             }
@@ -132,11 +132,11 @@ internal sealed class HeaderMatcherPolicy : MatcherPolicy, IEndpointComparerPoli
         return matchMode switch
         {
             HeaderMatchMode.ExactHeader => MemoryExtensions.Equals(requestHeaderValue, metadataHeaderValue, comparison),
-            HeaderMatchMode.HeaderPrefix => requestHeaderValue != null && metadataHeaderValue != null
+            HeaderMatchMode.HeaderPrefix => requestHeaderValue is not null && metadataHeaderValue is not null
                 && MemoryExtensions.StartsWith(requestHeaderValue, metadataHeaderValue, comparison),
-            HeaderMatchMode.Contains => requestHeaderValue != null && metadataHeaderValue != null
+            HeaderMatchMode.Contains => requestHeaderValue is not null && metadataHeaderValue is not null
                 && MemoryExtensions.Contains(requestHeaderValue, metadataHeaderValue, comparison),
-            HeaderMatchMode.NotContains => requestHeaderValue != null && metadataHeaderValue != null
+            HeaderMatchMode.NotContains => requestHeaderValue is not null && metadataHeaderValue is not null
                 && !MemoryExtensions.Contains(requestHeaderValue, metadataHeaderValue, comparison),
             _ => throw new NotImplementedException(matchMode.ToString()),
         };

src/ReverseProxy/Routing/ProxyEndpointFactory.cs

@@ -44,12 +44,12 @@ internal sealed class ProxyEndpointFactory
 
         endpointBuilder.Metadata.Add(route);
 
-        if (match.Hosts != null && match.Hosts.Count != 0)
+        if (match.Hosts is not null && match.Hosts.Count != 0)
         {
             endpointBuilder.Metadata.Add(new HostAttribute(match.Hosts.ToArray()));
         }
 
-        if (match.Headers != null && match.Headers.Count > 0)
+        if (match.Headers is not null && match.Headers.Count > 0)
         {
             var matchers = new List<HeaderMatcher>(match.Headers.Count);
             foreach (var header in match.Headers)
@@ -60,7 +60,7 @@ internal sealed class ProxyEndpointFactory
             endpointBuilder.Metadata.Add(new HeaderMetadata(matchers));
         }
 
-        if (match.QueryParameters != null && match.QueryParameters.Count > 0)
+        if (match.QueryParameters is not null && match.QueryParameters.Count > 0)
         {
             var matchers = new List<QueryParameterMatcher>(match.QueryParameters.Count);
             foreach (var queryparam in match.QueryParameters)
@@ -92,7 +92,7 @@ internal sealed class ProxyEndpointFactory
             acceptCorsPreflight = false;
         }
 
-        if (match.Methods != null && match.Methods.Count > 0)
+        if (match.Methods is not null && match.Methods.Count > 0)
         {
             endpointBuilder.Metadata.Add(new HttpMethodMetadata(match.Methods, acceptCorsPreflight));
         }

src/ReverseProxy/Routing/QueryParameterMatcher.cs

@@ -22,7 +22,7 @@ internal sealed class QueryParameterMatcher
             throw new ArgumentException("A query parameter name is required.", nameof(name));
         }
         if (mode != QueryParameterMatchMode.Exists
-            && (values == null || values.Count == 0))
+            && (values is null || values.Count == 0))
         {
             throw new ArgumentException("Query parameter values must have at least one value.", nameof(values));
         }

src/ReverseProxy/Routing/QueryParameterMatcherPolicy.cs

@@ -60,7 +60,7 @@ internal sealed class QueryParameterMatcherPolicy : MatcherPolicy, IEndpointComp
 
             var matchers = candidates[i].Endpoint.Metadata.GetMetadata<IQueryParameterMetadata>()?.Matchers;
 
-            if (matchers == null)
+            if (matchers is null)
             {
                 continue;
             }
@@ -132,11 +132,11 @@ internal sealed class QueryParameterMatcherPolicy : MatcherPolicy, IEndpointComp
         return matchMode switch
         {
             QueryParameterMatchMode.Exact => MemoryExtensions.Equals(requestQueryParameterValue, metadataQueryParameterValue, comparison),
-            QueryParameterMatchMode.Prefix => requestQueryParameterValue != null && metadataQueryParameterValue != null
+            QueryParameterMatchMode.Prefix => requestQueryParameterValue is not null && metadataQueryParameterValue is not null
                 && MemoryExtensions.StartsWith(requestQueryParameterValue, metadataQueryParameterValue, comparison),
-            QueryParameterMatchMode.Contains => requestQueryParameterValue != null && metadataQueryParameterValue != null
+            QueryParameterMatchMode.Contains => requestQueryParameterValue is not null && metadataQueryParameterValue is not null
                 && MemoryExtensions.Contains(requestQueryParameterValue, metadataQueryParameterValue, comparison),
-            QueryParameterMatchMode.NotContains => requestQueryParameterValue != null && metadataQueryParameterValue != null
+            QueryParameterMatchMode.NotContains => requestQueryParameterValue is not null && metadataQueryParameterValue is not null
                 && !MemoryExtensions.Contains(requestQueryParameterValue, metadataQueryParameterValue, comparison),
             _ => throw new NotImplementedException(matchMode.ToString()),
         };

src/ReverseProxy/Routing/ReverseProxyIEndpointRouteBuilderExtensions.cs

@@ -61,7 +61,7 @@ public static class ReverseProxyIEndpointRouteBuilderExtensions
     private static ProxyConfigManager GetOrCreateDataSource(IEndpointRouteBuilder endpoints)
     {
         var dataSource = endpoints.DataSources.OfType<ProxyConfigManager>().FirstOrDefault();
-        if (dataSource == null)
+        if (dataSource is null)
         {
             dataSource = endpoints.ServiceProvider.GetRequiredService<ProxyConfigManager>();
             endpoints.DataSources.Add(dataSource);

src/ReverseProxy/SessionAffinity/AffinitizeTransform.cs

@@ -28,7 +28,7 @@ internal sealed class AffinitizeTransform : ResponseTransform
         var options = proxyFeature.Cluster.Config.SessionAffinity;
         // The transform should only be added to routes that have affinity enabled.
         // However, the cluster can be re-assigned dynamically.
-        if (options == null || !options.Enabled.GetValueOrDefault())
+        if (options is null || !options.Enabled.GetValueOrDefault())
         {
             return default;
         }

src/ReverseProxy/SessionAffinity/AffinitizeTransformProvider.cs

@@ -47,7 +47,7 @@ internal sealed class AffinitizeTransformProvider : ITransformProvider
     {
         var options = context.Cluster?.SessionAffinity;
 
-        if (options != null && options.Enabled.GetValueOrDefault())
+        if (options is not null && options.Enabled.GetValueOrDefault())
         {
             var policy = _sessionAffinityPolicies.GetRequiredServiceById(options.Policy, SessionAffinityConstants.Policies.Cookie);
             context.ResponseTransforms.Add(new AffinitizeTransform(policy));

src/ReverseProxy/SessionAffinity/BaseSessionAffinityPolicy.cs

@@ -50,7 +50,7 @@ internal abstract class BaseSessionAffinityPolicy<T> : ISessionAffinityPolicy
 
         var requestAffinityKey = GetRequestAffinityKey(context, cluster, config);
 
-        if (requestAffinityKey.Key == null)
+        if (requestAffinityKey.Key is null)
         {
             return new AffinityResult(null, requestAffinityKey.ExtractedSuccessfully ? AffinityStatus.AffinityKeyNotSet : AffinityStatus.AffinityKeyExtractionFailed);
         }
@@ -70,7 +70,7 @@ internal abstract class BaseSessionAffinityPolicy<T> : ISessionAffinityPolicy
                 }
             }
 
-            if (matchingDestinations == null)
+            if (matchingDestinations is null)
             {
                 Log.DestinationMatchingToAffinityKeyNotFound(Logger, cluster.ClusterId);
             }
@@ -81,7 +81,7 @@ internal abstract class BaseSessionAffinityPolicy<T> : ISessionAffinityPolicy
         }
 
         // Empty destination list passed to this method is handled the same way as if no matching destinations are found.
-        if (matchingDestinations == null)
+        if (matchingDestinations is null)
         {
             return new AffinityResult(null, AffinityStatus.DestinationNotFound);
         }
@@ -121,7 +121,7 @@ internal abstract class BaseSessionAffinityPolicy<T> : ISessionAffinityPolicy
             var keyBytes = Convert.FromBase64String(Pad(encryptedRequestKey));
 
             var decryptedKeyBytes = _dataProtector.Unprotect(keyBytes);
-            if (decryptedKeyBytes == null)
+            if (decryptedKeyBytes is null)
             {
                 Log.RequestAffinityKeyDecryptionFailed(Logger, null);
                 return (Key: null, ExtractedSuccessfully: false);

src/ReverseProxy/SessionAffinity/CookieSessionAffinityPolicy.cs

@@ -48,7 +48,7 @@ internal sealed class CookieSessionAffinityPolicy : BaseSessionAffinityPolicy<st
             Domain = config.Cookie?.Domain,
             IsEssential = config.Cookie?.IsEssential ?? false,
             Secure = config.Cookie?.SecurePolicy == CookieSecurePolicy.Always || (config.Cookie?.SecurePolicy == CookieSecurePolicy.SameAsRequest && context.Request.IsHttps),
-            Expires = config.Cookie?.Expiration != null ? _clock.GetUtcNow().Add(config.Cookie.Expiration.Value) : default(DateTimeOffset?),
+            Expires = config.Cookie?.Expiration is not null ? _clock.GetUtcNow().Add(config.Cookie.Expiration.Value) : default(DateTimeOffset?),
         };
         context.Response.Cookies.Append(config.AffinityKeyName, Protect(unencryptedKey), affinityCookieOptions);
     }

src/ReverseProxy/SessionAffinity/SessionAffinityMiddleware.cs

@@ -40,7 +40,7 @@ internal sealed class SessionAffinityMiddleware
 
         var config = proxyFeature.Cluster.Config.SessionAffinity;
 
-        if (config == null || !config.Enabled.GetValueOrDefault())
+        if (config is null || !config.Enabled.GetValueOrDefault())
         {
             return _next(context);
         }

src/ReverseProxy/Transforms/Builder/StructuredTransformer.cs

@@ -137,7 +137,7 @@ internal sealed class StructuredTransformer : HttpTransformer
         // Only run the transforms if trailers are actually supported by the client response.
         var responseTrailersFeature = httpContext.Features.Get<IHttpResponseTrailersFeature>();
         var outgoingTrailers = responseTrailersFeature?.Trailers;
-        if (outgoingTrailers != null && !outgoingTrailers.IsReadOnly)
+        if (outgoingTrailers is not null && !outgoingTrailers.IsReadOnly)
         {
             var transformContext = new ResponseTrailersTransformContext()
             {

src/ReverseProxy/Transforms/ForwardedTransformExtensions.cs

@@ -30,22 +30,22 @@ public static class ForwardedTransformExtensions
         {
             transform[ForwardedTransformFactory.XForwardedKey] = xDefault.ToString();
 
-            if (xFor != null)
+            if (xFor is not null)
             {
                 transform[ForwardedTransformFactory.ForKey] = xFor.Value.ToString();
             }
 
-            if (xPrefix != null)
+            if (xPrefix is not null)
             {
                 transform[ForwardedTransformFactory.PrefixKey] = xPrefix.Value.ToString();
             }
 
-            if (xHost != null)
+            if (xHost is not null)
             {
                 transform[ForwardedTransformFactory.HostKey] = xHost.Value.ToString();
             }
 
-            if (xProto != null)
+            if (xProto is not null)
             {
                 transform[ForwardedTransformFactory.ProtoKey] = xProto.Value.ToString();
             }

src/ReverseProxy/Transforms/PathStringTransform.cs

@@ -19,7 +19,7 @@ public class PathStringTransform : RequestTransform
     /// <param name="value">The path value used to update the existing value.</param>
     public PathStringTransform(PathTransformMode mode, PathString value)
     {
-        if (value.Value == null)
+        if (value.Value is null)
         {
             throw new ArgumentNullException(nameof(value));
         }

src/ReverseProxy/Transforms/PathTransformExtensions.cs

@@ -20,7 +20,7 @@ public static class PathTransformExtensions
     /// </summary>
     public static RouteConfig WithTransformPathSet(this RouteConfig route, PathString path)
     {
-        if (path.Value == null)
+        if (path.Value is null)
         {
             throw new ArgumentNullException(nameof(path));
         }
@@ -45,7 +45,7 @@ public static class PathTransformExtensions
     /// </summary>
     public static RouteConfig WithTransformPathPrefix(this RouteConfig route, PathString prefix)
     {
-        if (prefix.Value == null)
+        if (prefix.Value is null)
         {
             throw new ArgumentNullException(nameof(prefix));
         }
@@ -70,7 +70,7 @@ public static class PathTransformExtensions
     /// </summary>
     public static RouteConfig WithTransformPathRemovePrefix(this RouteConfig route, PathString prefix)
     {
-        if (prefix.Value == null)
+        if (prefix.Value is null)
         {
             throw new ArgumentNullException(nameof(prefix));
         }
@@ -95,7 +95,7 @@ public static class PathTransformExtensions
     /// </summary>
     public static RouteConfig WithTransformPathRouteValues(this RouteConfig route, PathString pattern)
     {
-        if (pattern.Value == null)
+        if (pattern.Value is null)
         {
             throw new ArgumentNullException(nameof(pattern));
         }
@@ -111,7 +111,7 @@ public static class PathTransformExtensions
     /// </summary>
     public static TransformBuilderContext AddPathRouteValues(this TransformBuilderContext context, PathString pattern)
     {
-        if (pattern.Value == null)
+        if (pattern.Value is null)
         {
             throw new ArgumentNullException(nameof(pattern));
         }

src/ReverseProxy/Transforms/PathTransformFactory.cs

@@ -56,7 +56,7 @@ internal sealed class PathTransformFactory : ITransformFactory
 
     private void CheckPathNotNull(TransformRouteValidationContext context, string fieldName, string? path)
     {
-        if (path == null)
+        if (path is null)
         {
             context.Errors.Add(new ArgumentNullException(fieldName));
         }
@@ -99,7 +99,7 @@ internal sealed class PathTransformFactory : ITransformFactory
 
     private static PathString MakePathString(string path)
     {
-        if (path == null)
+        if (path is null)
         {
             throw new ArgumentNullException(nameof(path));
         }

src/ReverseProxy/Transforms/QueryParameterRemoveTransform.cs

@@ -26,7 +26,7 @@ public class QueryParameterRemoveTransform : RequestTransform
     /// <inheritdoc/>
     public override ValueTask ApplyAsync(RequestTransformContext context)
     {
-        if (context == null)
+        if (context is null)
         {
             throw new ArgumentNullException(nameof(context));
         }

src/ReverseProxy/Transforms/QueryParameterTransform.cs

@@ -27,13 +27,13 @@ public abstract class QueryParameterTransform : RequestTransform
     /// <inheritdoc/>
     public override ValueTask ApplyAsync(RequestTransformContext context)
     {
-        if (context == null)
+        if (context is null)
         {
             throw new ArgumentNullException(nameof(context));
         }
 
         var value = GetValue(context);
-        if (value != null)
+        if (value is not null)
         {
             switch (Mode)
             {

src/ReverseProxy/Transforms/QueryTransformContext.cs

@@ -30,7 +30,7 @@ public class QueryTransformContext
     {
         get
         {
-            if (_modifiedQueryParameters == null)
+            if (_modifiedQueryParameters is null)
             {
                 return _originalQueryString;
             }
@@ -50,7 +50,7 @@ public class QueryTransformContext
     {
         get
         {
-            if (_modifiedQueryParameters == null)
+            if (_modifiedQueryParameters is null)
             {
                 _modifiedQueryParameters = new Dictionary<string, StringValues>(_request.Query, StringComparer.OrdinalIgnoreCase);
             }

src/ReverseProxy/Transforms/RequestHeaderClientCertTransform.cs

@@ -34,7 +34,7 @@ public class RequestHeaderClientCertTransform : RequestTransform
         RemoveHeader(context, HeaderName);
 
         var clientCert = context.HttpContext.Connection.ClientCertificate;
-        if (clientCert != null)
+        if (clientCert is not null)
         {
             var encoded = Convert.ToBase64String(clientCert.RawData);
             AddHeader(context, HeaderName, encoded);

src/ReverseProxy/Transforms/RequestHeaderForwardedTransform.cs

@@ -148,7 +148,7 @@ public class RequestHeaderForwardedTransform : RequestTransform
         var addPort = port != 0 && (format == NodeFormat.IpAndPort || format == NodeFormat.UnknownAndPort || format == NodeFormat.RandomAndPort);
         var addRandomPort = (format == NodeFormat.IpAndRandomPort || format == NodeFormat.UnknownAndRandomPort || format == NodeFormat.RandomAndRandomPort);
         var ipv6 = (format == NodeFormat.Ip || format == NodeFormat.IpAndPort || format == NodeFormat.IpAndRandomPort)
-            && ipAddress != null && ipAddress.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6;
+            && ipAddress is not null && ipAddress.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6;
         var quote = addPort || addRandomPort || ipv6;
 
         if (quote)
@@ -161,7 +161,7 @@ public class RequestHeaderForwardedTransform : RequestTransform
             case NodeFormat.Ip:
             case NodeFormat.IpAndPort:
             case NodeFormat.IpAndRandomPort:
-                if (ipAddress != null)
+                if (ipAddress is not null)
                 {
                     if (ipv6)
                     {

src/ReverseProxy/Transforms/RequestHeaderXForwardedForTransform.cs

@@ -48,7 +48,7 @@ public class RequestHeaderXForwardedForTransform : RequestTransform
         {
             case ForwardedTransformActions.Set:
                 RemoveHeader(context, HeaderName);
-                if (remoteIp != null)
+                if (remoteIp is not null)
                 {
                     AddHeader(context, HeaderName, remoteIp);
                 }
@@ -69,7 +69,7 @@ public class RequestHeaderXForwardedForTransform : RequestTransform
     private void Append(RequestTransformContext context, string? remoteIp)
     {
         var existingValues = TakeHeader(context, HeaderName);
-        if (remoteIp == null)
+        if (remoteIp is null)
         {
             if (!string.IsNullOrEmpty(existingValues))
             {

src/ReverseProxy/Transforms/ResponseHeadersAllowedTransform.cs

@@ -41,7 +41,7 @@ public class ResponseHeadersAllowedTransform : ResponseTransform
             throw new ArgumentNullException(nameof(context));
         }
 
-        if (context.ProxyResponse == null)
+        if (context.ProxyResponse is null)
         {
             return default;
         }
@@ -51,7 +51,7 @@ public class ResponseHeadersAllowedTransform : ResponseTransform
         // See https://github.com/microsoft/reverse-proxy/blob/51d797986b1fea03500a1ad173d13a1176fb5552/src/ReverseProxy/Forwarder/HttpTransformer.cs#L67-L77
         var responseHeaders = context.HttpContext.Response.Headers;
         CopyResponseHeaders(context.ProxyResponse.Headers, responseHeaders);
-        if (context.ProxyResponse.Content != null)
+        if (context.ProxyResponse.Content is not null)
         {
             CopyResponseHeaders(context.ProxyResponse.Content.Headers, responseHeaders);
         }

src/ReverseProxy/Transforms/ResponseTrailerRemoveTransform.cs

@@ -37,7 +37,7 @@ public class ResponseTrailerRemoveTransform : ResponseTrailersTransform
             throw new ArgumentNullException(nameof(context));
         }
 
-        Debug.Assert(context.ProxyResponse != null);
+        Debug.Assert(context.ProxyResponse is not null);
 
         if (Condition == ResponseCondition.Always
             || Success(context) == (Condition == ResponseCondition.Success))
@@ -45,7 +45,7 @@ public class ResponseTrailerRemoveTransform : ResponseTrailersTransform
             var responseTrailersFeature = context.HttpContext.Features.Get<IHttpResponseTrailersFeature>();
             var responseTrailers = responseTrailersFeature?.Trailers;
             // Support should have already been checked by the caller.
-            Debug.Assert(responseTrailers != null);
+            Debug.Assert(responseTrailers is not null);
             Debug.Assert(!responseTrailers.IsReadOnly);
 
             responseTrailers.Remove(HeaderName);

src/ReverseProxy/Transforms/ResponseTrailersAllowedTransform.cs

@@ -42,7 +42,7 @@ public class ResponseTrailersAllowedTransform : ResponseTrailersTransform
             throw new ArgumentNullException(nameof(context));
         }
 
-        Debug.Assert(context.ProxyResponse != null);
+        Debug.Assert(context.ProxyResponse is not null);
         Debug.Assert(!context.HeadersCopied);
 
         // See https://github.com/microsoft/reverse-proxy/blob/51d797986b1fea03500a1ad173d13a1176fb5552/src/ReverseProxy/Forwarder/HttpTransformer.cs#L85-L99
@@ -50,7 +50,7 @@ public class ResponseTrailersAllowedTransform : ResponseTrailersTransform
         // because they lookup `IHttpResponseTrailersFeature` for every call. Here we do it just once instead.
         var responseTrailersFeature = context.HttpContext.Features.Get<IHttpResponseTrailersFeature>();
         var outgoingTrailers = responseTrailersFeature?.Trailers;
-        if (outgoingTrailers != null && !outgoingTrailers.IsReadOnly)
+        if (outgoingTrailers is not null && !outgoingTrailers.IsReadOnly)
         {
             // Note that trailers, if any, should already have been declared in Proxy's response
             CopyResponseHeaders(context.ProxyResponse.TrailingHeaders, outgoingTrailers);

src/ReverseProxy/Transforms/ResponseTrailersTransform.cs

@@ -43,12 +43,12 @@ public abstract class ResponseTrailersTransform
             throw new ArgumentException($"'{nameof(headerName)}' cannot be null or empty.", nameof(headerName));
         }
 
-        Debug.Assert(context.ProxyResponse != null);
+        Debug.Assert(context.ProxyResponse is not null);
 
         var responseTrailersFeature = context.HttpContext.Features.Get<IHttpResponseTrailersFeature>();
         var responseTrailers = responseTrailersFeature?.Trailers;
         // Support should have already been checked by the caller.
-        Debug.Assert(responseTrailers != null);
+        Debug.Assert(responseTrailers is not null);
         Debug.Assert(!responseTrailers.IsReadOnly);
 
         if (responseTrailers.TryGetValue(headerName, out var existingValues))
@@ -71,7 +71,7 @@ public abstract class ResponseTrailersTransform
         var responseTrailersFeature = context.HttpContext.Features.Get<IHttpResponseTrailersFeature>();
         var responseTrailers = responseTrailersFeature?.Trailers;
         // Support should have already been checked by the caller.
-        Debug.Assert(responseTrailers != null);
+        Debug.Assert(responseTrailers is not null);
         Debug.Assert(!responseTrailers.IsReadOnly);
 
         responseTrailers[headerName] = values;

src/ReverseProxy/Transforms/RouteConfigTransformExtensions.cs

@@ -24,7 +24,7 @@ public static class RouteConfigTransformExtensions
         }
 
         List<IReadOnlyDictionary<string, string>> transforms;
-        if (route.Transforms == null)
+        if (route.Transforms is null)
         {
             transforms = new List<IReadOnlyDictionary<string, string>>();
         }

src/ReverseProxy/Utilities/DelegatingStream.cs

@@ -64,7 +64,7 @@ internal abstract class DelegatingStream : Stream
 
     protected DelegatingStream(Stream innerStream)
     {
-        Debug.Assert(innerStream != null);
+        Debug.Assert(innerStream is not null);
         _innerStream = innerStream;
     }
 

src/ReverseProxy/Utilities/ParsedMetadataEntry.cs

@@ -26,14 +26,14 @@ internal sealed class ParsedMetadataEntry<T>
     public T GetParsedOrDefault(T defaultValue)
     {
         var currentValue = _value;
-        if (_cluster.Model.Config.Metadata != null && _cluster.Model.Config.Metadata.TryGetValue(_metadataName, out var stringValue))
+        if (_cluster.Model.Config.Metadata is not null && _cluster.Model.Config.Metadata.TryGetValue(_metadataName, out var stringValue))
         {
-            if (currentValue == null || currentValue.Item1 != stringValue)
+            if (currentValue is null || currentValue.Item1 != stringValue)
             {
                 _value = Tuple.Create<string?, T>(stringValue, _parser(stringValue, out var parsedValue) ? parsedValue : defaultValue);
             }
         }
-        else if (currentValue == null || currentValue.Item1 != null)
+        else if (currentValue is null || currentValue.Item1 is not null)
         {
             _value = Tuple.Create<string?, T>(null, defaultValue);
         }

src/ReverseProxy/Utilities/ServiceLookupHelper.cs

@@ -10,7 +10,7 @@ internal static class ServiceLookupHelper
 {
     public static IDictionary<string, T> ToDictionaryByUniqueId<T>(this IEnumerable<T> services, Func<T, string> idSelector)
     {
-        if (services == null)
+        if (services is null)
         {
             throw new ArgumentNullException(nameof(services));
         }

src/ReverseProxy/Utilities/TlsFrameHelper.cs

@@ -131,7 +131,7 @@ public static class TlsFrameHelper
         {
             get
             {
-                return _ciphers == null ? ReadOnlyMemory<TlsCipherSuite>.Empty : new ReadOnlyMemory<TlsCipherSuite>(_ciphers);
+                return _ciphers is null ? ReadOnlyMemory<TlsCipherSuite>.Empty : new ReadOnlyMemory<TlsCipherSuite>(_ciphers);
             }
         }
 

src/ReverseProxy/Utilities/ValueStringBuilder.cs

@@ -54,7 +54,7 @@ internal ref partial struct ValueStringBuilder
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
     public void Append(string s)
     {
-        if (s == null)
+        if (s is null)
         {
             return;
         }
@@ -111,7 +111,7 @@ internal ref partial struct ValueStringBuilder
 
         var toReturn = _arrayToReturnToPool;
         RawChars = _arrayToReturnToPool = poolArray;
-        if (toReturn != null)
+        if (toReturn is not null)
         {
             ArrayPool<char>.Shared.Return(toReturn);
         }
@@ -122,7 +122,7 @@ internal ref partial struct ValueStringBuilder
     {
         var toReturn = _arrayToReturnToPool;
         this = default; // for safety, to avoid using pooled array if this instance is erroneously appended to again
-        if (toReturn != null)
+        if (toReturn is not null)
         {
             ArrayPool<char>.Shared.Return(toReturn);
         }

test/Kubernetes.Tests/IngressCacheTests.cs

@@ -36,7 +36,7 @@ public class IngressCacheTests
     public void IngressWithClassAnnotationTests(string ingressClassName, string controllerName, bool? isDefault, int expectedIngressCount)
     {
         // Arrange
-        if (controllerName != null)
+        if (controllerName is not null)
         {
             var ingressClass = KubeResourceGenerator.CreateIngressClass(ingressClassName, controllerName, isDefault);
             _cacheUnderTest.Update(WatchEventType.Added, ingressClass);
@@ -64,7 +64,7 @@ public class IngressCacheTests
     public void IngressWithoutClassAnnotationTests(string ingressClassName, string controllerName, bool? isDefault, int expectedIngressCount)
     {
         // Arrange
-        if (controllerName != null)
+        if (controllerName is not null)
         {
             var ingressClass = KubeResourceGenerator.CreateIngressClass(ingressClassName, controllerName, isDefault);
             _cacheUnderTest.Update(WatchEventType.Added, ingressClass);

test/Kubernetes.Tests/IngressConversionTests.cs

@@ -129,7 +129,7 @@ public class IngressControllerTests
         typeMap.Add("v1/Service", typeof(V1Service));
         typeMap.Add("v1/Endpoints", typeof(V1Endpoints));
 
-        if (ingressClass != null)
+        if (ingressClass is not null)
         {
             cache.Update(WatchEventType.Added, ingressClass);
         }

test/ReverseProxy.FunctionalTests/Common/TestEnvironment.cs

@@ -163,7 +163,7 @@ public class TestEnvironment
                     .UseKestrel(kestrel =>
                     {
 #if NET
-                        if (requestHeaderEncoding != null)
+                        if (requestHeaderEncoding is not null)
                         {
                             kestrel.RequestHeaderEncodingSelector = _ => requestHeaderEncoding;
                         }

test/ReverseProxy.FunctionalTests/Expect100ContinueTests.cs

@@ -307,7 +307,7 @@ public class Expect100ContinueTests
                 Assert.Equal(0, contentStream.Position);
             }
 
-            if (responseAction != null)
+            if (responseAction is not null)
             {
                 await responseAction(response);
             }

test/ReverseProxy.FunctionalTests/WebSocketTests.cs

@@ -209,7 +209,7 @@ public class WebSocketTests
         static async Task RawUpgrade(HttpContext httpContext)
         {
             var upgradeFeature = httpContext.Features.Get<IHttpUpgradeFeature>();
-            if (upgradeFeature == null || !upgradeFeature.IsUpgradableRequest)
+            if (upgradeFeature is null || !upgradeFeature.IsUpgradableRequest)
             {
                 httpContext.Response.StatusCode = StatusCodes.Status426UpgradeRequired;
                 return;

test/ReverseProxy.Tests/Common/TestResources.cs

@@ -23,7 +23,7 @@ public static class TestResources
     {
         // On Windows, applications should not import PFX files in parallel to avoid a known system-level
         // race condition bug in native code which can cause crashes/corruption of the certificate state.
-        if (importPfxMutex != null)
+        if (importPfxMutex is not null)
         {
             Assert.True(importPfxMutex.WaitOne(MutexTimeout), "Cannot acquire the global certificate mutex.");
         }
@@ -42,12 +42,12 @@ public static class TestResources
     {
         var webProxy = new WebProxy(new System.Uri(address));
 
-        if (bypassOnLocal != null)
+        if (bypassOnLocal is not null)
         {
             webProxy.BypassProxyOnLocal = bypassOnLocal.Value;
         }
 
-        if (useDefaultCredentials != null)
+        if (useDefaultCredentials is not null)
         {
             webProxy.UseDefaultCredentials = useDefaultCredentials.Value;
         }
@@ -57,7 +57,7 @@ public static class TestResources
 
     public static string GetCertPath(string fileName)
     {
-        if (fileName == null)
+        if (fileName is null)
         {
             return null;
         }

test/ReverseProxy.Tests/Configuration/ConfigValidatorTests.cs

@@ -411,7 +411,7 @@ public class ConfigValidatorTests
         {
             Name = name,
             Mode = mode,
-            Values = value == null ? null : new[] { value },
+            Values = value is null ? null : new[] { value },
         };
 
         var route = new RouteConfig
@@ -444,7 +444,7 @@ public class ConfigValidatorTests
         {
             Name = name,
             Mode = mode,
-            Values = value == null ? null : new[] { value },
+            Values = value is null ? null : new[] { value },
         };
 
         var route = new RouteConfig
@@ -888,10 +888,10 @@ public class ConfigValidatorTests
                 Active = new ActiveHealthCheckConfig
                 {
                     Enabled = true,
-                    Interval = interval != null ? TimeSpan.FromSeconds(interval.Value) : (TimeSpan?)null,
+                    Interval = interval is not null ? TimeSpan.FromSeconds(interval.Value) : (TimeSpan?)null,
                     Path = path,
                     Policy = policy,
-                    Timeout = timeout != null ? TimeSpan.FromSeconds(timeout.Value) : (TimeSpan?)null
+                    Timeout = timeout is not null ? TimeSpan.FromSeconds(timeout.Value) : (TimeSpan?)null
                 }
             }
         };
@@ -918,9 +918,9 @@ public class ConfigValidatorTests
                 Active = new ActiveHealthCheckConfig
                 {
                     Enabled = true,
-                    Interval = interval != null ? TimeSpan.FromSeconds(interval.Value) : (TimeSpan?)null,
+                    Interval = interval is not null ? TimeSpan.FromSeconds(interval.Value) : (TimeSpan?)null,
                     Policy = policy,
-                    Timeout = timeout != null ? TimeSpan.FromSeconds(timeout.Value) : (TimeSpan?)null
+                    Timeout = timeout is not null ? TimeSpan.FromSeconds(timeout.Value) : (TimeSpan?)null
                 }
             }
         };
@@ -951,7 +951,7 @@ public class ConfigValidatorTests
                 {
                     Enabled = true,
                     Policy = policy,
-                    ReactivationPeriod = reactivationPeriod != null ? TimeSpan.FromSeconds(reactivationPeriod.Value) : (TimeSpan?)null
+                    ReactivationPeriod = reactivationPeriod is not null ? TimeSpan.FromSeconds(reactivationPeriod.Value) : (TimeSpan?)null
                 }
             }
         };
@@ -978,7 +978,7 @@ public class ConfigValidatorTests
                 {
                     Enabled = true,
                     Policy = policy,
-                    ReactivationPeriod = reactivationPeriod != null ? TimeSpan.FromSeconds(reactivationPeriod.Value) : (TimeSpan?)null
+                    ReactivationPeriod = reactivationPeriod is not null ? TimeSpan.FromSeconds(reactivationPeriod.Value) : (TimeSpan?)null
                 }
             }
         };

test/ReverseProxy.Tests/Health/ActiveHealthCheckMonitorTests.cs

@@ -672,7 +672,7 @@ public class ActiveHealthCheckMonitorTests
         httpClient.Setup(c => c.SendAsync(It.IsAny<HttpRequestMessage>(), It.IsAny<CancellationToken>()))
             .Returns((HttpRequestMessage m, CancellationToken c) =>
             {
-                if (cancellation != null)
+                if (cancellation is not null)
                 {
                     c.Register(_ => cancellation(), null);
                 }

test/ReverseProxy.Tests/Health/ConsecutiveFailuresHealthPolicyTests.cs

@@ -119,7 +119,7 @@ public class ConsecutiveFailuresHealthPolicyTests
 
     private ClusterState GetClusterInfo(string id, int destinationCount, int? failureThreshold = null)
     {
-        var metadata = failureThreshold != null
+        var metadata = failureThreshold is not null
             ? new Dictionary<string, string> { { ConsecutiveFailuresHealthPolicyOptions.ThresholdMetadataName, failureThreshold.ToString() } }
             : null;
         var clusterModel = new ClusterModel(

test/ReverseProxy.Tests/Health/DefaultProbingRequestFactoryTests.cs

@@ -42,7 +42,7 @@ public class DefaultProbingRequestFactoryTests
     [InlineData(null)]
     public void CreateRequest_RequestVersionProperties(string versionString)
     {
-        var version = versionString != null ? Version.Parse(versionString) : null;
+        var version = versionString is not null ? Version.Parse(versionString) : null;
         var clusterModel = GetClusterConfig("cluster0",
             new ActiveHealthCheckConfig()
             {

test/ReverseProxy.Tests/Health/TransportFailureRateHealthPolicyTests.cs

@@ -247,7 +247,7 @@ public class TransportFailureRateHealthPolicyTests
 
     private ClusterState GetClusterInfo(string id, int destinationCount, double? failureRateLimit = null, TimeSpan? reactivationPeriod = null)
     {
-        var metadata = failureRateLimit != null
+        var metadata = failureRateLimit is not null
             ? new Dictionary<string, string> { { TransportFailureRateHealthPolicyOptions.FailureRateLimitMetadataName, failureRateLimit?.ToString(CultureInfo.InvariantCulture) } }
             : null;
         var clusterModel = new ClusterModel(

test/ReverseProxy.Tests/Management/ProxyConfigManagerTests.cs

@@ -732,7 +732,7 @@ public class ProxyConfigManagerTests
         public ValueTask<RouteConfig> ConfigureRouteAsync(RouteConfig route, ClusterConfig cluster, CancellationToken cancel)
         {
             string order;
-            if (cluster != null)
+            if (cluster is not null)
             {
                 order = cluster.Metadata["Order"];
             }

test/ReverseProxy.Tests/Routing/HeaderMatcherPolicyTests.cs

@@ -156,7 +156,7 @@ public class HeaderMatcherPolicyTests
     public async Task ApplyAsync_MatchingScenarios_AnyHeaderValue(string incomingHeaderValue, bool shouldMatch)
     {
         var context = new DefaultHttpContext();
-        if (incomingHeaderValue != null)
+        if (incomingHeaderValue is not null)
         {
             context.Request.Headers.Add("org-id", incomingHeaderValue);
         }
@@ -238,7 +238,7 @@ public class HeaderMatcherPolicyTests
         bool shouldMatch)
     {
         var context = new DefaultHttpContext();
-        if (incomingHeaderValue != null)
+        if (incomingHeaderValue is not null)
         {
             context.Request.Headers.Add("org-id", incomingHeaderValue);
         }

test/ReverseProxy.Tests/Routing/QueryMatcherPolicyTests.cs

@@ -161,7 +161,7 @@ public class QueryParameterMatcherPolicyTests
     public async Task ApplyAsync_MatchingScenarios_AnyQueryParamValue(string incomingQueryParamValue, bool shouldMatch)
     {
         var context = new DefaultHttpContext();
-        if (incomingQueryParamValue != null)
+        if (incomingQueryParamValue is not null)
         {
             var queryStr = "?org-id=" + incomingQueryParamValue;
             context.Request.QueryString = new QueryString(queryStr);
@@ -246,7 +246,7 @@ public class QueryParameterMatcherPolicyTests
         bool shouldMatch)
     {
         var context = new DefaultHttpContext();
-        if (incomingQueryParamValue != null)
+        if (incomingQueryParamValue is not null)
         {
             var queryStr = "?org-id=" + incomingQueryParamValue;
             context.Request.QueryString = new QueryString(queryStr);

test/ReverseProxy.Tests/SessionAffinity/BaseSessionAffinityPolicyTests.cs

@@ -54,14 +54,14 @@ public class BaseSesstionAffinityPolicyTests
         Assert.Equal(expectedStatus, affinityResult.Status);
         Assert.Same(expectedDestination, affinityResult.Destinations?.FirstOrDefault());
 
-        if (expectedLogLevel != null)
+        if (expectedLogLevel is not null)
         {
             logger.Verify(
                 l => l.Log(expectedLogLevel.Value, expectedEventId, It.IsAny<It.IsAnyType>(), It.IsAny<Exception>(), (Func<It.IsAnyType, Exception, string>)It.IsAny<object>()),
                 Times.Once);
         }
 
-        if (expectedDestination != null)
+        if (expectedDestination is not null)
         {
             Assert.Equal(1, affinityResult.Destinations.Count);
         }

test/ReverseProxy.Tests/SessionAffinity/SessionAffinityMiddlewareTests.cs

@@ -40,7 +40,7 @@ public class SessionAffinityMiddlewareTests
         var cluster = GetCluster();
         var endpoint = GetEndpoint(cluster);
         DestinationState foundDestination = null;
-        if (foundDestinationId != null)
+        if (foundDestinationId is not null)
         {
             cluster.Destinations.TryGetValue(foundDestinationId, out foundDestination);
         }
@@ -72,7 +72,7 @@ public class SessionAffinityMiddlewareTests
         policies[0].VerifyNoOtherCalls();
         policies[1].VerifyAll();
 
-        if (foundDestinationId != null)
+        if (foundDestinationId is not null)
         {
             Assert.Equal(1, destinationFeature.AvailableDestinations.Count);
             Assert.Equal(foundDestinationId, destinationFeature.AvailableDestinations[0].DestinationId);

testassets/ReverseProxy.Direct/Startup.cs

@@ -60,7 +60,7 @@ public class Startup
             {
                 await httpProxy.SendAsync(httpContext, "https://example.com", httpClient, requestConfig, transformer);
                 var errorFeature = httpContext.GetForwarderErrorFeature();
-                if (errorFeature != null)
+                if (errorFeature is not null)
                 {
                     var error = errorFeature.Error;
                     var exception = errorFeature.Exception;

testassets/TestClient/Program.cs

@@ -24,7 +24,7 @@ internal class Program
             // Do nothing, we will show help right after.
         }
 
-        if (parsedArgs == null || parsedArgs.Help)
+        if (parsedArgs is null || parsedArgs.Help)
         {
             CommandLineArgs.ShowHelp();
             return 1;

testassets/TestServer/Controllers/HttpController.cs

@@ -96,7 +96,7 @@ public class HttpController : ControllerBase
     public async Task Stress([FromQuery] int delay, [FromQuery] int responseSize)
     {
         var bodyReader = Request.BodyReader;
-        if (bodyReader != null)
+        if (bodyReader is not null)
         {
             while (true)
             {
@@ -114,7 +114,7 @@ public class HttpController : ControllerBase
         }
 
         var bodyWriter = Response.BodyWriter;
-        if (bodyWriter != null && responseSize > 0)
+        if (bodyWriter is not null && responseSize > 0)
         {
             const int WriteBufferSize = 4096;