diff --git a/modules/openapi-generator/src/main/resources/csharp-netcore/RetryConfiguration.mustache b/modules/openapi-generator/src/main/resources/csharp-netcore/RetryConfiguration.mustache
index 29aa6092681..4cc953487a8 100644
--- a/modules/openapi-generator/src/main/resources/csharp-netcore/RetryConfiguration.mustache
+++ b/modules/openapi-generator/src/main/resources/csharp-netcore/RetryConfiguration.mustache
@@ -1,3 +1,5 @@
+{{>partial_header}}
+
 using Polly;
 {{#useRestSharp}}
 using RestSharp;
@@ -11,7 +13,7 @@ namespace {{packageName}}.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
 {{#useRestSharp}}
         /// <summary>
diff --git a/samples/client/others/csharp-netcore-complex-files/src/Org.OpenAPITools/Client/RetryConfiguration.cs b/samples/client/others/csharp-netcore-complex-files/src/Org.OpenAPITools/Client/RetryConfiguration.cs
index c93633a36d9..f589a4482da 100644
--- a/samples/client/others/csharp-netcore-complex-files/src/Org.OpenAPITools/Client/RetryConfiguration.cs
+++ b/samples/client/others/csharp-netcore-complex-files/src/Org.OpenAPITools/Client/RetryConfiguration.cs
@@ -1,3 +1,13 @@
+/*
+ * MultipartFile test
+ *
+ * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+
 using Polly;
 using RestSharp;
 
@@ -6,7 +16,7 @@ namespace Org.OpenAPITools.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
         /// <summary>
         /// Retry policy
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-ConditionalSerialization/src/Org.OpenAPITools/Client/RetryConfiguration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-ConditionalSerialization/src/Org.OpenAPITools/Client/RetryConfiguration.cs
index c93633a36d9..91bc7cc6d54 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-ConditionalSerialization/src/Org.OpenAPITools/Client/RetryConfiguration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-ConditionalSerialization/src/Org.OpenAPITools/Client/RetryConfiguration.cs
@@ -1,3 +1,13 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+
 using Polly;
 using RestSharp;
 
@@ -6,7 +16,7 @@ namespace Org.OpenAPITools.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
         /// <summary>
         /// Retry policy
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/RetryConfiguration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/RetryConfiguration.cs
index 285b6dac105..139ef334aa0 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/RetryConfiguration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-httpclient/src/Org.OpenAPITools/Client/RetryConfiguration.cs
@@ -1,3 +1,13 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+
 using Polly;
 using System.Net.Http;
 
@@ -6,7 +16,7 @@ namespace Org.OpenAPITools.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
         /// <summary>
         /// Retry policy
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-net47/src/Org.OpenAPITools/Client/RetryConfiguration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-net47/src/Org.OpenAPITools/Client/RetryConfiguration.cs
index c93633a36d9..91bc7cc6d54 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-net47/src/Org.OpenAPITools/Client/RetryConfiguration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-net47/src/Org.OpenAPITools/Client/RetryConfiguration.cs
@@ -1,3 +1,13 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+
 using Polly;
 using RestSharp;
 
@@ -6,7 +16,7 @@ namespace Org.OpenAPITools.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
         /// <summary>
         /// Retry policy
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient-net5.0/src/Org.OpenAPITools/Client/RetryConfiguration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient-net5.0/src/Org.OpenAPITools/Client/RetryConfiguration.cs
index c93633a36d9..91bc7cc6d54 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient-net5.0/src/Org.OpenAPITools/Client/RetryConfiguration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient-net5.0/src/Org.OpenAPITools/Client/RetryConfiguration.cs
@@ -1,3 +1,13 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+
 using Polly;
 using RestSharp;
 
@@ -6,7 +16,7 @@ namespace Org.OpenAPITools.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
         /// <summary>
         /// Retry policy
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/RetryConfiguration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/RetryConfiguration.cs
index c93633a36d9..91bc7cc6d54 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/RetryConfiguration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClient/src/Org.OpenAPITools/Client/RetryConfiguration.cs
@@ -1,3 +1,13 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+
 using Polly;
 using RestSharp;
 
@@ -6,7 +16,7 @@ namespace Org.OpenAPITools.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
         /// <summary>
         /// Retry policy
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/RetryConfiguration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/RetryConfiguration.cs
index c93633a36d9..91bc7cc6d54 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/RetryConfiguration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClientCore/src/Org.OpenAPITools/Client/RetryConfiguration.cs
@@ -1,3 +1,13 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This spec is mainly for testing Petstore server and contains fake endpoints, models. Please do not use this for any other purpose. Special characters: \" \\
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+
 using Polly;
 using RestSharp;
 
@@ -6,7 +16,7 @@ namespace Org.OpenAPITools.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
         /// <summary>
         /// Retry policy
diff --git a/samples/client/petstore/csharp-netcore/OpenAPIClientCoreAndNet47/src/Org.OpenAPITools/Client/RetryConfiguration.cs b/samples/client/petstore/csharp-netcore/OpenAPIClientCoreAndNet47/src/Org.OpenAPITools/Client/RetryConfiguration.cs
index c93633a36d9..92d8f878ca0 100644
--- a/samples/client/petstore/csharp-netcore/OpenAPIClientCoreAndNet47/src/Org.OpenAPITools/Client/RetryConfiguration.cs
+++ b/samples/client/petstore/csharp-netcore/OpenAPIClientCoreAndNet47/src/Org.OpenAPITools/Client/RetryConfiguration.cs
@@ -1,3 +1,13 @@
+/*
+ * OpenAPI Petstore
+ *
+ * This is a sample server Petstore server. For this sample, you can use the api key `special-key` to test the authorization filters.
+ *
+ * The version of the OpenAPI document: 1.0.0
+ * Generated by: https://github.com/openapitools/openapi-generator.git
+ */
+
+
 using Polly;
 using RestSharp;
 
@@ -6,7 +16,7 @@ namespace Org.OpenAPITools.Client
     /// <summary>
     /// Configuration class to set the polly retry policies to be applied to the requests.
     /// </summary>
-    public class RetryConfiguration
+    public static class RetryConfiguration
     {
         /// <summary>
         /// Retry policy