regenerate C# protos
diff --git a/src/csharp/Grpc.IntegrationTesting/Empty.cs b/src/csharp/Grpc.IntegrationTesting/Empty.cs
index 9bf2b8f..4323c5a 100644
--- a/src/csharp/Grpc.IntegrationTesting/Empty.cs
+++ b/src/csharp/Grpc.IntegrationTesting/Empty.cs
@@ -1,5 +1,5 @@
 // Generated by the protocol buffer compiler.  DO NOT EDIT!
-// source: test/proto/empty.proto
+// source: src/proto/grpc/testing/empty.proto
 #pragma warning disable 1591, 0612, 3021
 #region Designer generated code
 
@@ -9,40 +9,48 @@
 using scg = global::System.Collections.Generic;
 namespace Grpc.Testing {
 
-  namespace Proto {
+  /// <summary>Holder for reflection information generated from src/proto/grpc/testing/empty.proto</summary>
+  [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+  public static partial class EmptyReflection {
 
-    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
-    public static partial class Empty {
-
-      #region Descriptor
-      public static pbr::FileDescriptor Descriptor {
-        get { return descriptor; }
-      }
-      private static pbr::FileDescriptor descriptor;
-
-      static Empty() {
-        byte[] descriptorData = global::System.Convert.FromBase64String(
-            string.Concat(
-              "ChZ0ZXN0L3Byb3RvL2VtcHR5LnByb3RvEgxncnBjLnRlc3RpbmciBwoFRW1w", 
-              "dHliBnByb3RvMw=="));
-        descriptor = pbr::FileDescriptor.InternalBuildGeneratedFileFrom(descriptorData,
-            new pbr::FileDescriptor[] { },
-            new pbr::GeneratedCodeInfo(null, new pbr::GeneratedCodeInfo[] {
-              new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.Empty), null, null, null, null)
-            }));
-      }
-      #endregion
-
+    #region Descriptor
+    /// <summary>File descriptor for src/proto/grpc/testing/empty.proto</summary>
+    public static pbr::FileDescriptor Descriptor {
+      get { return descriptor; }
     }
+    private static pbr::FileDescriptor descriptor;
+
+    static EmptyReflection() {
+      byte[] descriptorData = global::System.Convert.FromBase64String(
+          string.Concat(
+            "CiJzcmMvcHJvdG8vZ3JwYy90ZXN0aW5nL2VtcHR5LnByb3RvEgxncnBjLnRl",
+            "c3RpbmciBwoFRW1wdHliBnByb3RvMw=="));
+      descriptor = pbr::FileDescriptor.FromGeneratedCode(descriptorData,
+          new pbr::FileDescriptor[] { },
+          new pbr::GeneratedCodeInfo(null, new pbr::GeneratedCodeInfo[] {
+            new pbr::GeneratedCodeInfo(typeof(global::Grpc.Testing.Empty), global::Grpc.Testing.Empty.Parser, null, null, null, null)
+          }));
+    }
+    #endregion
+
   }
   #region Messages
+  /// <summary>
+  ///  An empty message that you can re-use to avoid defining duplicated empty
+  ///  messages in your project. A typical example is to use it as argument or the
+  ///  return value of a service API. For instance:
+  ///
+  ///    service Foo {
+  ///      rpc Bar (grpc.testing.Empty) returns (grpc.testing.Empty) { };
+  ///    };
+  /// </summary>
   [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
   public sealed partial class Empty : pb::IMessage<Empty> {
     private static readonly pb::MessageParser<Empty> _parser = new pb::MessageParser<Empty>(() => new Empty());
     public static pb::MessageParser<Empty> Parser { get { return _parser; } }
 
     public static pbr::MessageDescriptor Descriptor {
-      get { return global::Grpc.Testing.Proto.Empty.Descriptor.MessageTypes[0]; }
+      get { return global::Grpc.Testing.EmptyReflection.Descriptor.MessageTypes[0]; }
     }
 
     pbr::MessageDescriptor pb::IMessage.Descriptor {
@@ -82,7 +90,7 @@
     }
 
     public override string ToString() {
-      return pb::JsonFormatter.Default.Format(this);
+      return pb::JsonFormatter.ToDiagnosticString(this);
     }
 
     public void WriteTo(pb::CodedOutputStream output) {