diff -r d90c3cbf13df -r e1117321adaf src/hotspot/share/jfr/metadata/metadata.xml
--- a/src/hotspot/share/jfr/metadata/metadata.xml	Thu Jun 28 15:06:55 2018 +0200
+++ b/src/hotspot/share/jfr/metadata/metadata.xml	Thu Jun 28 15:13:39 2018 +0200
@@ -577,6 +577,7 @@
   <Event name="OldObjectSample" category="Java Application" label="Old Object Sample" description="A potential memory leak" stackTrace="true" thread="true"
     startTime="false" cutoff="true">
     <Field type="Ticks" name="allocationTime" label="Allocation Time" />
+    <Field type="ulong" contentType="bytes" name="lastKnownHeapUsage" label="Last Known Heap Usage" />
     <Field type="OldObject" name="object" label="Object" />
     <Field type="int" name="arrayElements" label="Array Elements" description="If the object is an array, the number of elements, or -1 if it is not an array" />
     <Field type="OldObjectGcRoot" name="root" label="GC Root" />
@@ -1132,4 +1133,4 @@
   <XmlContentType name="percentage" annotationType="jdk.jfr.Percentage" />
   <XmlContentType name="millis" annotationType="jdk.jfr.Timespan" annotationValue="MILLISECONDS" />
 
-</Metadata>
\ No newline at end of file
+</Metadata>