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

@@ -203,10 +203,11 @@
      */
     private final transient String calendarType;
     /**
      * Serialization version.
      */
+    @java.io.Serial
     private static final long serialVersionUID = 3127340209035924785L;
     /**
      * Singleton instance of the Islamic Umm Al-Qura calendar of Saudi Arabia.
      * Other Hijrah chronology variants may be available from
      * {@link Chronology#getAvailableChronologies}.

@@ -1019,19 +1020,21 @@
      * </pre>
      *
      * @return the instance of {@code Ser}, not null
      */
     @Override
+    @java.io.Serial
     Object writeReplace() {
         return super.writeReplace();
     }
 
     /**
      * 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");
     }
 }