code: public DiscriminatorColumn<Entity<T>> getOrCreateDiscriminatorColumn()
     {
        Node node = childNode.getOrCreate("discriminator-column");
        DiscriminatorColumn<Entity<T>> discriminatorColumn = new DiscriminatorColumnImpl<Entity<T>>(this, "discriminator-column", childNode, node);
        return discriminatorColumn;
     }
docs: If not already created, a new <code>discriminator-column</code> element with the given value will be created.
  Otherwise, the existing <code>discriminator-column</code> element will be returned.
  @return  a new or existing instance of <code>DiscriminatorColumn<Entity<T>></code>