src/jdk.hotspot.agent/share/classes/sun/jvm/hotspot/gc/shared/CollectedHeap.java

@@ -56,12 +56,12 @@
   /** Returns the lowest address of the heap. */
   public Address start() {
     return reservedRegion().start();
   }
 
-  public long capacity() { return 0; }
-  public long used()     { return 0; }
+  public abstract long capacity();
+  public abstract long used();
 
   public MemRegion reservedRegion() {
     return new MemRegion(addr.addOffsetTo(reservedFieldOffset));
   }