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

@@ -128,10 +128,11 @@
         implements ChronoLocalDate, Serializable {
 
     /**
      * Serialization version.
      */
+    @java.io.Serial
     private static final long serialVersionUID = -305327627230580483L;
 
     /**
      * The underlying ISO local date.
      */

@@ -717,10 +718,11 @@
      * 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");
     }
 
     /**

@@ -734,10 +736,11 @@
      *  out.writeByte(get(DAY_OF_MONTH));
      * </pre>
      *
      * @return the instance of {@code Ser}, not null
      */
+    @java.io.Serial
     private Object writeReplace() {
         return new Ser(Ser.JAPANESE_DATE_TYPE, this);
     }
 
     void writeExternal(DataOutput out) throws IOException {