Work around incorrect implementation of WithMultiplexingStream

This method was corrected for 16.8 Preview 3.

src/Workspaces/Remote/Core/ServiceDescriptor.cs

@@ -6,6 +6,7 @@
 
 using System;
 using System.IO.Pipelines;
+using System.Reflection;
 using MessagePack;
 using MessagePack.Resolvers;
 using Microsoft.ServiceHub.Framework;
@@ -78,6 +79,26 @@ protected override JsonRpcConnection CreateConnection(JsonRpc jsonRpc)
             return connection;
         }
 
+        public override ServiceRpcDescriptor WithMultiplexingStream(MultiplexingStream? multiplexingStream)
+        {
+            var baseResult = base.WithMultiplexingStream(multiplexingStream);
+            if (baseResult is ServiceDescriptor)
+                return baseResult;
+
+            // work around incorrect implementation in 16.8 Preview 2
+            if (MultiplexingStream == multiplexingStream)
+                return this;
+
+            var result = (ServiceDescriptor)Clone();
+            typeof(ServiceRpcDescriptor).GetProperty(nameof(MultiplexingStream))!.SetValue(result, multiplexingStream);
+            if (result.MultiplexingStreamOptions is null)
+                return result;
+
+            result = (ServiceDescriptor)result.Clone();
+            typeof(ServiceJsonRpcDescriptor).GetProperty(nameof(MultiplexingStreamOptions))!.SetValue(result, value: null);
+            return result;
+        }
+
         internal static class TestAccessor
         {
             public static MessagePackSerializerOptions Options => s_options;