plugins: msgpack codec should use cty tags

plugins/base/plugin.go

@@ -52,7 +52,9 @@ func (p *PluginBase) GRPCClient(ctx context.Context, broker *plugin.GRPCBroker,
 
 // MsgpackHandle is a shared handle for encoding/decoding of structs
 var MsgpackHandle = func() *codec.MsgpackHandle {
-	h := &codec.MsgpackHandle{RawToString: true}
+	h := &codec.MsgpackHandle{}
+	h.RawToString = true
+	h.TypeInfos = codec.NewTypeInfos([]string{"cty", "codec"})
 	h.MapType = reflect.TypeOf(map[string]interface{}(nil))
 	return h
 }()