<class name="domainModel.ShoppingCart" table="ShoppingCart">
  <id name="ID" column="CartID" type="int" unsaved-value="0">
    <generator class="identity"/>
  </id>

  <bag name="Items" table="ShoppingCart" cascade="all">
    <key column="CartID"/>
    <composite-element class="domainModel.CartItem">
      <property name="Quantity" column="Quantity" type="int"/>

      <many-to-one name="Product" column="ProductID"/>
    </composite-element>
  </bag>

  <many-to-one name="Customer" column="CustomerID"/>
</class>

class ShoppingCart {

  private int cartId;
  private ArrayList items = new ArrayList
  private Customer customer;

  public ArrayList getItems() {
    return items;
  }

  public void setItems(ArrayList items) {
    this.items = items;
  }

  ...

}

class Item {

  private int quantity;
  private Product product;

  public int getQuantity() {
    return quantity;
  }

  public void setQuantity(int quantity) {
    this.quantity = quantity;
  }

  ...
}