src/java.base/share/classes/java/lang/ref/FinalReference.java

*** 1,7 ****
  /*
!  * Copyright (c) 1997, 2013, 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
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
--- 1,7 ----
  /*
!  * Copyright (c) 1997, 2017, 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
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
*** 31,36 ****
--- 31,41 ----
  class FinalReference<T> extends Reference<T> {
  
      public FinalReference(T referent, ReferenceQueue<? super T> q) {
          super(referent, q);
      }
+ 
+     @Override
+     public boolean enqueue() {
+         throw new UnsupportedOperationException("should never reach here");
+     }
  }