src/java.base/share/classes/jdk/internal/util/ReferencedKeyMap.java

@@ -1,7 +1,7 @@
  /*
-  * Copyright (c) 2023, Oracle and/or its affiliates. All rights reserved.
+  * Copyright (c) 2023, 2024, 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

@@ -46,10 +46,11 @@
  /**
   * This class provides management of {@link Map maps} where it is desirable to
   * remove entries automatically when the key is garbage collected. This is
   * accomplished by using a backing map where the keys are either a
   * {@link WeakReference} or a {@link SoftReference}.
+  * Keys must be {@linkplain Class#isIdentity() identity objects.}
   * <p>
   * To create a {@link ReferencedKeyMap} the user must provide a {@link Supplier}
   * of the backing map and whether {@link WeakReference} or
   * {@link SoftReference} is to be used.
   *