diff -r b026a43e1809 -r 31ec3e55fa3d src/hotspot/share/jfr/recorder/checkpoint/types/jfrTypeSetUtils.hpp
--- a/src/hotspot/share/jfr/recorder/checkpoint/types/jfrTypeSetUtils.hpp	Tue Oct 29 09:34:23 2019 +0800
+++ b/src/hotspot/share/jfr/recorder/checkpoint/types/jfrTypeSetUtils.hpp	Tue Oct 29 11:33:25 2019 +0100
@@ -99,12 +99,6 @@
 };
 
 template <typename T>
-class Stub {
- public:
-  bool operator()(T const& value) { return true; }
-};
-
-template <typename T>
 class SerializePredicate {
   bool _class_unload;
  public: