add PersistenceUnitUtil.getVersion()

see jakartaee#74

api/src/main/java/jakarta/persistence/PersistenceUnitUtil.java

@@ -163,4 +163,16 @@ public interface PersistenceUnitUtil extends PersistenceUtil {
      *          to be an entity
      */
     public Object getIdentifier(Object entity);
-} 
+
+    /**
+     *  Return the version of the entity.
+     *  A generated version is not guaranteed to be available until after
+     *  the database insert has occurred.
+     *  Returns null if the entity does not yet have an id.
+     *  @param entity  entity instance
+     *  @return id of the entity
+     *  @throws IllegalArgumentException if the object is found not
+     *          to be an entity
+     */
+    public Object getVersion(Object entity);
+}