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

*** 752,761 ****
--- 752,762 ----
      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).
*** 763,772 ****
--- 764,774 ----
       * @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();
*** 788,797 ****
--- 790,800 ----
      /**
       * 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();