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

*** 89,98 ****
--- 89,99 ----
  final class Ser implements Externalizable {
  
      /**
       * Serialization version.
       */
+     @java.io.Serial
      private static final long serialVersionUID = -7683839454370182990L;
  
      static final byte DURATION_TYPE = 1;
      static final byte INSTANT_TYPE = 2;
      static final byte LOCAL_DATE_TYPE = 3;
*** 275,284 ****
--- 276,286 ----
      /**
       * Returns the object that will replace this one.
       *
       * @return the read object, should never be null
       */
+     @java.io.Serial
      private Object readResolve() {
           return object;
      }
  
  }