regenerate C# code
diff --git a/src/csharp/Grpc.IntegrationTesting/ServicesGrpc.cs b/src/csharp/Grpc.IntegrationTesting/ServicesGrpc.cs
index 42bf5e0..f7071eb 100644
--- a/src/csharp/Grpc.IntegrationTesting/ServicesGrpc.cs
+++ b/src/csharp/Grpc.IntegrationTesting/ServicesGrpc.cs
@@ -111,12 +111,12 @@
       ///  One request followed by one response.
       ///  The server returns the client payload as-is.
       /// </summary>
-      Task<global::Grpc.Testing.SimpleResponse> UnaryCall(global::Grpc.Testing.SimpleRequest request, ServerCallContext context);
+      global::System.Threading.Tasks.Task<global::Grpc.Testing.SimpleResponse> UnaryCall(global::Grpc.Testing.SimpleRequest request, ServerCallContext context);
       /// <summary>
       ///  One request followed by one response.
       ///  The server returns the client payload as-is.
       /// </summary>
-      Task StreamingCall(IAsyncStreamReader<global::Grpc.Testing.SimpleRequest> requestStream, IServerStreamWriter<global::Grpc.Testing.SimpleResponse> responseStream, ServerCallContext context);
+      global::System.Threading.Tasks.Task StreamingCall(IAsyncStreamReader<global::Grpc.Testing.SimpleRequest> requestStream, IServerStreamWriter<global::Grpc.Testing.SimpleResponse> responseStream, ServerCallContext context);
     }
 
     /// <summary>Base class for server-side implementations of BenchmarkService</summary>
@@ -126,7 +126,7 @@
       ///  One request followed by one response.
       ///  The server returns the client payload as-is.
       /// </summary>
-      public virtual Task<global::Grpc.Testing.SimpleResponse> UnaryCall(global::Grpc.Testing.SimpleRequest request, ServerCallContext context)
+      public virtual global::System.Threading.Tasks.Task<global::Grpc.Testing.SimpleResponse> UnaryCall(global::Grpc.Testing.SimpleRequest request, ServerCallContext context)
       {
         throw new RpcException(new Status(StatusCode.Unimplemented, ""));
       }
@@ -135,7 +135,7 @@
       ///  One request followed by one response.
       ///  The server returns the client payload as-is.
       /// </summary>
-      public virtual Task StreamingCall(IAsyncStreamReader<global::Grpc.Testing.SimpleRequest> requestStream, IServerStreamWriter<global::Grpc.Testing.SimpleResponse> responseStream, ServerCallContext context)
+      public virtual global::System.Threading.Tasks.Task StreamingCall(IAsyncStreamReader<global::Grpc.Testing.SimpleRequest> requestStream, IServerStreamWriter<global::Grpc.Testing.SimpleResponse> responseStream, ServerCallContext context)
       {
         throw new RpcException(new Status(StatusCode.Unimplemented, ""));
       }
@@ -375,7 +375,7 @@
       ///  and once the shutdown has finished, the OK status is sent to terminate
       ///  this RPC.
       /// </summary>
-      Task RunServer(IAsyncStreamReader<global::Grpc.Testing.ServerArgs> requestStream, IServerStreamWriter<global::Grpc.Testing.ServerStatus> responseStream, ServerCallContext context);
+      global::System.Threading.Tasks.Task RunServer(IAsyncStreamReader<global::Grpc.Testing.ServerArgs> requestStream, IServerStreamWriter<global::Grpc.Testing.ServerStatus> responseStream, ServerCallContext context);
       /// <summary>
       ///  Start client with specified workload.
       ///  First request sent specifies the ClientConfig followed by ClientStatus
@@ -384,15 +384,15 @@
       ///  and once the shutdown has finished, the OK status is sent to terminate
       ///  this RPC.
       /// </summary>
-      Task RunClient(IAsyncStreamReader<global::Grpc.Testing.ClientArgs> requestStream, IServerStreamWriter<global::Grpc.Testing.ClientStatus> responseStream, ServerCallContext context);
+      global::System.Threading.Tasks.Task RunClient(IAsyncStreamReader<global::Grpc.Testing.ClientArgs> requestStream, IServerStreamWriter<global::Grpc.Testing.ClientStatus> responseStream, ServerCallContext context);
       /// <summary>
       ///  Just return the core count - unary call
       /// </summary>
-      Task<global::Grpc.Testing.CoreResponse> CoreCount(global::Grpc.Testing.CoreRequest request, ServerCallContext context);
+      global::System.Threading.Tasks.Task<global::Grpc.Testing.CoreResponse> CoreCount(global::Grpc.Testing.CoreRequest request, ServerCallContext context);
       /// <summary>
       ///  Quit this worker
       /// </summary>
-      Task<global::Grpc.Testing.Void> QuitWorker(global::Grpc.Testing.Void request, ServerCallContext context);
+      global::System.Threading.Tasks.Task<global::Grpc.Testing.Void> QuitWorker(global::Grpc.Testing.Void request, ServerCallContext context);
     }
 
     /// <summary>Base class for server-side implementations of WorkerService</summary>
@@ -406,7 +406,7 @@
       ///  and once the shutdown has finished, the OK status is sent to terminate
       ///  this RPC.
       /// </summary>
-      public virtual Task RunServer(IAsyncStreamReader<global::Grpc.Testing.ServerArgs> requestStream, IServerStreamWriter<global::Grpc.Testing.ServerStatus> responseStream, ServerCallContext context)
+      public virtual global::System.Threading.Tasks.Task RunServer(IAsyncStreamReader<global::Grpc.Testing.ServerArgs> requestStream, IServerStreamWriter<global::Grpc.Testing.ServerStatus> responseStream, ServerCallContext context)
       {
         throw new RpcException(new Status(StatusCode.Unimplemented, ""));
       }
@@ -419,7 +419,7 @@
       ///  and once the shutdown has finished, the OK status is sent to terminate
       ///  this RPC.
       /// </summary>
-      public virtual Task RunClient(IAsyncStreamReader<global::Grpc.Testing.ClientArgs> requestStream, IServerStreamWriter<global::Grpc.Testing.ClientStatus> responseStream, ServerCallContext context)
+      public virtual global::System.Threading.Tasks.Task RunClient(IAsyncStreamReader<global::Grpc.Testing.ClientArgs> requestStream, IServerStreamWriter<global::Grpc.Testing.ClientStatus> responseStream, ServerCallContext context)
       {
         throw new RpcException(new Status(StatusCode.Unimplemented, ""));
       }
@@ -427,7 +427,7 @@
       /// <summary>
       ///  Just return the core count - unary call
       /// </summary>
-      public virtual Task<global::Grpc.Testing.CoreResponse> CoreCount(global::Grpc.Testing.CoreRequest request, ServerCallContext context)
+      public virtual global::System.Threading.Tasks.Task<global::Grpc.Testing.CoreResponse> CoreCount(global::Grpc.Testing.CoreRequest request, ServerCallContext context)
       {
         throw new RpcException(new Status(StatusCode.Unimplemented, ""));
       }
@@ -435,7 +435,7 @@
       /// <summary>
       ///  Quit this worker
       /// </summary>
-      public virtual Task<global::Grpc.Testing.Void> QuitWorker(global::Grpc.Testing.Void request, ServerCallContext context)
+      public virtual global::System.Threading.Tasks.Task<global::Grpc.Testing.Void> QuitWorker(global::Grpc.Testing.Void request, ServerCallContext context)
       {
         throw new RpcException(new Status(StatusCode.Unimplemented, ""));
       }