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

@@ -182,10 +182,11 @@
     }
 
     /**
      * Serialization version.
      */
+    @java.io.Serial
     private static final long serialVersionUID = 2287754244819255394L;
 
     /**
      * The local date-time.
      */

@@ -1929,20 +1930,22 @@
      *  // the <a href="{@docRoot}/serialized-form.html#java.time.ZoneOffset">offset</a> excluding the one byte header
      * </pre>
      *
      * @return the instance of {@code Ser}, not null
      */
+    @java.io.Serial
     private Object writeReplace() {
         return new Ser(Ser.OFFSET_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 {