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

@@ -101,10 +101,11 @@
         implements  ChronoLocalDateTime<D>, Temporal, TemporalAdjuster, Serializable {
 
     /**
      * Serialization version.
      */
+    @java.io.Serial
     private static final long serialVersionUID = 4556003607393004514L;
     /**
      * Hours per day.
      */
     static final int HOURS_PER_DAY = 24;

@@ -407,20 +408,22 @@
      *  out.witeObject(toLocalTime());
      * </pre>
      *
      * @return the instance of {@code Ser}, not null
      */
+   @java.io.Serial
     private Object writeReplace() {
         return new Ser(Ser.CHRONO_LOCAL_DATE_TIME_TYPE, this);
     }
 
     /**
      * 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");
     }
 
     void writeExternal(ObjectOutput out) throws IOException {