src/java.base/share/classes/java/util/EnumMap.java

@@ -752,10 +752,11 @@
     private static <K extends Enum<K>> K[] getKeyUniverse(Class<K> keyType) {
         return SharedSecrets.getJavaLangAccess()
                                         .getEnumConstantsShared(keyType);
     }
 
+    @java.io.Serial
     private static final long serialVersionUID = 458661240069192865L;
 
     /**
      * Save the state of the {@code EnumMap} instance to a stream (i.e.,
      * serialize it).

@@ -763,10 +764,11 @@
      * @serialData The <i>size</i> of the enum map (the number of key-value
      *             mappings) is emitted (int), followed by the key (Object)
      *             and value (Object) for each key-value mapping represented
      *             by the enum map.
      */
+    @java.io.Serial
     private void writeObject(java.io.ObjectOutputStream s)
         throws java.io.IOException
     {
         // Write out the key type and any hidden stuff
         s.defaultWriteObject();

@@ -788,10 +790,11 @@
     /**
      * Reconstitute the {@code EnumMap} instance from a stream (i.e.,
      * deserialize it).
      */
     @SuppressWarnings("unchecked")
+    @java.io.Serial
     private void readObject(java.io.ObjectInputStream s)
         throws java.io.IOException, ClassNotFoundException
     {
         // Read in the key type and any hidden stuff
         s.defaultReadObject();