src/java.base/share/classes/java/time/chrono/JapaneseEra.java

*** 164,173 ****
--- 164,174 ----
      private static final int N_ERA_CONSTANTS = REIWA.getValue() + ERA_OFFSET;
  
      /**
       * Serialization version.
       */
+     @java.io.Serial
      private static final long serialVersionUID = 1466499369062886794L;
  
      // array for the singleton JapaneseEra instances
      private static final JapaneseEra[] KNOWN_ERAS;
  
*** 424,433 ****
--- 425,435 ----
       * Defend against malicious streams.
       *
       * @param s the stream to read
       * @throws InvalidObjectException always
       */
+     @java.io.Serial
      private void readObject(ObjectInputStream s) throws InvalidObjectException {
          throw new InvalidObjectException("Deserialization via serialization delegate");
      }
  
      //-----------------------------------------------------------------------
*** 440,449 ****
--- 442,452 ----
       *  out.writeInt(getValue());
       * </pre>
       *
       * @return the instance of {@code Ser}, not null
       */
+     @java.io.Serial
      private Object writeReplace() {
          return new Ser(Ser.JAPANESE_ERA_TYPE, this);
      }
  
      void writeExternal(DataOutput out) throws IOException {