add license header

Signed-off-by: Benjamin Wang <[email protected]>

pkg/legacygwjsonpb/marshal.go

@@ -1,3 +1,20 @@
+// Copyright (c) 2015, Gengo, Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without modification,
+// are permitted provided that the following conditions are met:
+//
+// * Redistributions of source code must retain the above copyright notice,
+// this list of conditions and the following disclaimer.
+//
+// * Redistributions in binary form must reproduce the above copyright notice,
+// this list of conditions and the following disclaimer in the documentation
+// and/or other materials provided with the distribution.
+//
+// * Neither the name of Gengo, Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from this
+// software without specific prior written permission.
+
 package legacygwjsonpb
 
 import (