--- old/src/java.logging/share/classes/java/util/logging/Level.java	2020-08-13 11:48:45.000000000 +0100
+++ new/src/java.logging/share/classes/java/util/logging/Level.java	2020-08-13 11:48:45.000000000 +0100
@@ -1,5 +1,5 @@
 /*
- * 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
@@ -25,6 +25,7 @@
 
 package java.util.logging;
 
+import java.io.Serial;
 import java.lang.ref.Reference;
 import java.lang.ref.ReferenceQueue;
 import java.lang.ref.WeakReference;
@@ -432,11 +433,25 @@
         return value;
     }
 
+    @Serial
     private static final long serialVersionUID = -8176160795706313070L;
 
-    // Serialization magic to prevent "doppelgangers".
-    // This is a performance optimization.
+    /**
+     * 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.
         Optional<Level> level = KnownLevel.matches(this);
         if (level.isPresent()) {
             return level.get();