src/java.logging/share/classes/java/util/logging/Level.java

@@ -1,7 +1,7 @@
 /*
- * Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2000, 2020, 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

@@ -23,10 +23,11 @@
  * questions.
  */
 
 package java.util.logging;
 
+import java.io.Serial;
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.WeakReference;
 import java.security.AccessController;
 import java.security.PrivilegedAction;

@@ -430,15 +431,29 @@
      */
     public final int intValue() {
         return value;
     }
 
+    @Serial
     private static final long serialVersionUID = -8176160795706313070L;
 
+    /**
+     * This method prevents creating two different instances of
+     * {@code Level} with the same characteristics.
+     * If a matching level is found in the local system that corresponds
+     * to the deserialized object, the deserialized object is replaced
+     * by the existing instance. Otherwise, a new instance of {@code Level}
+     * is created and substituted to the deserialized object.
+     * The returned {@code Level} instance will have the same {@code name},
+     * {@code value}, and {@code resourceBundleName} as the deserialized
+     * object, but no further guarantee is made.
+     * @return A {@code Level} instance with equivalent characteristics.
+     */
+    @Serial
+    private Object readResolve() {
     // Serialization magic to prevent "doppelgangers".
     // This is a performance optimization.
-    private Object readResolve() {
         Optional<Level> level = KnownLevel.matches(this);
         if (level.isPresent()) {
             return level.get();
         }
         // Woops.  Whoever sent us this object knows