use auto-generated header for C# plugin
diff --git a/src/compiler/csharp_generator.cc b/src/compiler/csharp_generator.cc
index 40fe0b0..7c97056 100644
--- a/src/compiler/csharp_generator.cc
+++ b/src/compiler/csharp_generator.cc
@@ -659,8 +659,11 @@
     }
 
     // Write out a file header.
-    out.Print("// Generated by the protocol buffer compiler.  DO NOT EDIT!\n");
-    out.Print("// source: $filename$\n", "filename", file->name());
+    out.Print("// <auto-generated>\n");
+    out.Print(
+        "//     Generated by the protocol buffer compiler.  DO NOT EDIT!\n");
+    out.Print("//     source: $filename$\n", "filename", file->name());
+    out.Print("// </auto-generated>\n");
 
     // use C++ style as there are no file-level XML comments in .NET
     grpc::string leading_comments = GetCsharpComments(file, true);