--- old/src/hotspot/share/classfile/compactHashtable.hpp	2018-08-03 16:41:10.000000000 -0500
+++ new/src/hotspot/share/classfile/compactHashtable.hpp	2018-08-03 16:41:10.000000000 -0500
@@ -231,6 +231,10 @@
 
   // For reading from/writing to the CDS archive
   void serialize(SerializeClosure* soc);
+
+  inline bool empty() {
+    return (_entry_count == 0);
+  }
 };
 
 template <class T, class N> class CompactHashtable : public SimpleCompactHashtable {