Improve example for ServerCertificateValidationCallback

Author: ManickaP

snippets/csharp/System.Net.Http/WinHttpHandler/Project.csproj

@@ -0,0 +1,8 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Library</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+  </PropertyGroup>
+   
+</Project>

snippets/csharp/System.Net.Http/WinHttpHandler/program.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Net;
+using System.Net.Http;
+using System.Net.Sockets;
+using System.Threading.Tasks;
+
+class HttpClientHandler_SecureExample
+{
+    static async Task Main()
+    {
+        // <Snippet1>
+        var handler = new WinHttpHandler();
+        handler.ServerCertificateValidationCallback = (httpRequestMessage, certificate, chain, sslPolicyErrors)
+        {
+             if (sslPolicyErrors == SslPolicyErrors.None)
+                return true;
+
+            Console.WriteLine("Certificate error: {0}", sslPolicyErrors);
+
+            // Do not allow this client to communicate with unauthenticated servers.
+            return false;
+        }
+        // </Snippet1>
+    }
+}

xml/System.Net.Http/WinHttpHandler.xml

@@ -747,6 +747,12 @@ When this property is set to `true`, all HTTP redirect responses from the server
 ## Remarks
  The default value is `null`. If this property is `null`, the server certificate is validated using standard well-known certificate authorities.
 
+ The delegate's `sslPolicyErrors` argument contains any certificate errors returned by SSPI while authenticating the server. The <xref:System.Boolean> value returned by this delegate determines whether the authentication is allowed to succeed.
+
+## Examples
+ The following code example implements the callback. If there are validation errors, this method displays them and returns `false`, which prevents communication with the unauthenticated server.
+
+ :::code language="csharp" source="~/snippets/csharp/System.Net.Http/WinHttpHandler/program.cs" id="Snippet1":::
  ]]></format>
         </remarks>
       </Docs>