[VOL-4290] Voltha go library updates for gRPC migration

Change-Id: I1aa2774beb6b7ed7419bc45aeb53fcae8a8ecda0
diff --git a/vendor/github.com/json-iterator/go/reflect_struct_encoder.go b/vendor/github.com/json-iterator/go/reflect_struct_encoder.go
index d0759cf..152e3ef 100644
--- a/vendor/github.com/json-iterator/go/reflect_struct_encoder.go
+++ b/vendor/github.com/json-iterator/go/reflect_struct_encoder.go
@@ -200,6 +200,7 @@
 
 func (encoder *stringModeStringEncoder) Encode(ptr unsafe.Pointer, stream *Stream) {
 	tempStream := encoder.cfg.BorrowStream(nil)
+	tempStream.Attachment = stream.Attachment
 	defer encoder.cfg.ReturnStream(tempStream)
 	encoder.elemEncoder.Encode(ptr, tempStream)
 	stream.WriteString(string(tempStream.Buffer()))