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

@@ -727,20 +727,22 @@
      *  out.writeUTF(getId());
      * </pre>
      *
      * @return the instance of {@code Ser}, not null
      */
+    @java.io.Serial
     Object writeReplace() {
         return new Ser(Ser.CHRONO_TYPE, this);
     }
 
     /**
      * Defend against malicious streams.
      *
      * @param s the stream to read
      * @throws java.io.InvalidObjectException always
      */
+    @java.io.Serial
     private void readObject(ObjectInputStream s) throws ObjectStreamException {
         throw new InvalidObjectException("Deserialization via serialization delegate");
     }
 
     void writeExternal(DataOutput out) throws IOException {