--- old/src/java.base/share/classes/java/time/chrono/ChronoZonedDateTimeImpl.java	2019-08-27 17:28:38.034324386 -0700
+++ new/src/java.base/share/classes/java/time/chrono/ChronoZonedDateTimeImpl.java	2019-08-27 17:28:37.862324386 -0700
@@ -107,6 +107,7 @@
     /**
      * Serialization version.
      */
+    @java.io.Serial
     private static final long serialVersionUID = -5261813987200935591L;
 
     /**
@@ -333,6 +334,7 @@
      *
      * @return the instance of {@code Ser}, not null
      */
+    @java.io.Serial
     private Object writeReplace() {
         return new Ser(Ser.CHRONO_ZONE_DATE_TIME_TYPE, this);
     }
@@ -343,6 +345,7 @@
      * @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");
     }