src/java.base/share/classes/java/util/JapaneseImperialCalendar.java

@@ -249,10 +249,11 @@
         2*ONE_HOUR      // DST_OFFSET (double summer time)
     };
 
     // Proclaim serialization compatibility with JDK 1.6
     @SuppressWarnings("FieldNameHidesFieldInSuperclass")
+    @java.io.Serial
     private static final long serialVersionUID = -3364572813905467929L;
 
     static {
         Era[] es = jcal.getEras();
         int length = es.length + 1;

@@ -2389,10 +2390,11 @@
     }
 
     /**
      * Updates internal state.
      */
+    @java.io.Serial
     private void readObject(ObjectInputStream stream)
             throws IOException, ClassNotFoundException {
         stream.defaultReadObject();
         if (jdate == null) {
             jdate = jcal.newCalendarDate(getZone());