Initial commit.

Wino.Core/Http/MicrosoftImmutableIdHandler.cs

@@ -0,0 +1,19 @@
+using System.Net.Http;
+using System.Threading;
+using System.Threading.Tasks;
+
+namespace Wino.Core.Http
+{
+    /// <summary>
+    /// Adds additional Prefer header for immutable id support in the Graph service client.
+    /// </summary>
+    public class MicrosoftImmutableIdHandler : DelegatingHandler
+    {
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            request.Headers.TryAddWithoutValidation("Prefer", "IdType=\"ImmutableId\"");
+
+            return base.SendAsync(request, cancellationToken);
+        }
+    }
+}