Regenete csharp sample

Author: jpfinne

samples/client/petstore/csharp/generichost/latest/NullTypes/src/Org.OpenAPITools/Client/ClientUtils.cs

@@ -301,6 +301,35 @@ public static bool IsJsonMime(string mime)
             throw new JsonException("The specified discriminator was not found.");
         }
 
+        /// <summary>
+        /// Determines if the provided header is a content header
+        /// </summary>
+        /// <param name="header">The header to check</param>
+        /// <returns>True if a content header; False otherwise</returns>
+        public static bool IsContentHeader(string header)
+        {
+            return ContentHeaders.Contains(header.ToLowerInvariant());
+        }
+
+        /// <summary>
+        /// The collection of content headers as per
+        /// https://learn.microsoft.com/en-us/dotnet/api/system.net.http.httpcontent.headers
+        /// </summary>
+        private static readonly string[] ContentHeaders = new String[] 
+        {
+            "allow",
+            "content-encoding",
+            "content-disposition",
+            "content-language",
+            "content-length",
+            "content-location",
+            "content-md5",
+            "content-range",
+            "content-type",
+            "expires",
+            "last-modified"
+        };
+
         /// <summary>
         /// The base path of the API
         /// </summary>