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

@@ -129,10 +129,11 @@
   * This class is immutable and thread-safe.
   *
   * @since 1.8
   */
  @jdk.internal.ValueBased
+ @jdk.internal.MigratedValueClass
  public final class Duration
          implements TemporalAmount, Comparable<Duration>, Serializable {
  
      /**
       * Constant for a duration of zero.