Fix a json serializer bug.

libraries/Microsoft.Bot.Connector.Streaming/Session/StreamingSession.cs

@@ -9,7 +9,6 @@
 using System.Linq;
 using System.Net;
 using System.Runtime.InteropServices;
-using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Bot.Connector.Streaming.Payloads;
@@ -19,6 +18,8 @@
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
 using Microsoft.Net.Http.Headers;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
 
 namespace Microsoft.Bot.Connector.Streaming.Session
 {
@@ -42,6 +43,13 @@ internal class StreamingSession
 
         private readonly object _receiveSync = new object();
 
+        static StreamingSession()
+        {
+            var tmpSetting = SerializationSettings.DefaultSerializationSettings;
+            tmpSetting.NullValueHandling = NullValueHandling.Ignore;
+            Serializer = JsonSerializer.Create(tmpSetting);            
+        }
+
         public StreamingSession(RequestHandler receiver, TransportHandler sender, ILogger logger, CancellationToken connectionCancellationToken = default)
         {
             _receiver = receiver ?? throw new ArgumentNullException(nameof(receiver));
@@ -52,6 +60,8 @@ public StreamingSession(RequestHandler receiver, TransportHandler sender, ILogge
             _connectionCancellationToken = connectionCancellationToken;
         }
 
+        private static JsonSerializer Serializer { get; }
+
         public async Task<ReceiveResponse> SendRequestAsync(StreamingRequest request, CancellationToken cancellationToken)
         {
             if (request == null)
@@ -461,10 +471,16 @@ private static T DeserializeTo<T>(ReadOnlySequence<byte> payload)
                     mainPayload = payload.Slice(_utf8Bom.Length);
                 }
 
-                var reader = new Utf8JsonReader(mainPayload);
-                return System.Text.Json.JsonSerializer.Deserialize<T>(
-                    ref reader,
-                    new JsonSerializerOptions() { IgnoreNullValues = true, PropertyNameCaseInsensitive = true });
+                using (var ms = new MemoryStream(mainPayload.ToArray()))
+                {
+                    using (var sr = new StreamReader(ms))
+                    {
+                        using (var jsonReader = new JsonTextReader(sr))
+                        {
+                            return Serializer.Deserialize<T>(jsonReader);
+                        }                        
+                    }                    
+                }
             }
 
             private static void CreatePlaceholderStreams(Header header, List<IContentStream> placeholders, List<StreamDescription> streamInfo)