--- old/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/CollectedHeap.java	2018-11-26 21:28:22.894991967 +0100
+++ new/src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/CollectedHeap.java	2018-11-26 21:28:22.741993317 +0100
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2000, 2015, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -75,6 +75,10 @@
 
   public abstract CollectedHeapName kind();
 
+  public int cell_header_size() {
+    return 0;
+  }
+
   public String oopAddressDescription(OopHandle handle) {
       return handle.toString();
   }