code: public PersistenceUnitDefaults<PersistenceUnitMetadata<T>> getOrCreatePersistenceUnitDefaults()
     {
        Node node = childNode.getOrCreate("persistence-unit-defaults");
        PersistenceUnitDefaults<PersistenceUnitMetadata<T>> persistenceUnitDefaults = new PersistenceUnitDefaultsImpl<PersistenceUnitMetadata<T>>(this, "persistence-unit-defaults", childNode, node);
        return persistenceUnitDefaults;
     }
docs: If not already created, a new <code>persistence-unit-defaults</code> element with the given value will be created.
  Otherwise, the existing <code>persistence-unit-defaults</code> element will be returned.
  @return  a new or existing instance of <code>PersistenceUnitDefaults<PersistenceUnitMetadata<T>></code>