src/java.base/share/classes/java/time/Instant.java

*** 243,252 ****
--- 243,253 ----
      public static final Instant MAX = Instant.ofEpochSecond(MAX_SECOND, 999_999_999);
  
      /**
       * Serialization version.
       */
+     @java.io.Serial
      private static final long serialVersionUID = -665713676816604388L;
  
      /**
       * The number of seconds from the epoch of 1970-01-01T00:00:00Z.
       */
*** 1340,1359 ****
--- 1341,1362 ----
       *  out.writeInt(nanos);
       * </pre>
       *
       * @return the instance of {@code Ser}, not null
       */
+     @java.io.Serial
      private Object writeReplace() {
          return new Ser(Ser.INSTANT_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(DataOutput out) throws IOException {