--- old/src/java.base/share/classes/java/time/chrono/JapaneseDate.java	2019-08-27 17:28:40.734324386 -0700
+++ new/src/java.base/share/classes/java/time/chrono/JapaneseDate.java	2019-08-27 17:28:40.546324386 -0700
@@ -130,6 +130,7 @@
     /**
      * Serialization version.
      */
+    @java.io.Serial
     private static final long serialVersionUID = -305327627230580483L;
 
     /**
@@ -719,6 +720,7 @@
      * @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");
     }
@@ -736,6 +738,7 @@
      *
      * @return the instance of {@code Ser}, not null
      */
+    @java.io.Serial
     private Object writeReplace() {
         return new Ser(Ser.JAPANESE_DATE_TYPE, this);
     }