hibernate的left join on问题
我有2个表，一个shop 还有一个shopcoupon 2者一对多关联关系，shop里面有2个数据，shopcoupon有且只有一条数据对应shop表，我用left join on 语句查询数据，按理说应该返回2条数据吧？，但是只返回了1条数据，而且好像还是2个对象类型的，我打印出来时2个实体对象类型的，是怎么回事啊？
相关代码：
shop.hbm.xml
-------------------------------------
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
  Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
  <class name="com.joint.joint_ddw.entity.DdwShop" table="ddw_shop" catalog="joint_ddw">
  <id name="shopid" type="java.lang.Integer">
  <column name="shopid" />
  <generator class="native" />
  </id>
  <property name="shopname" type="java.lang.String">
  <column name="shopname" length="40" not-null="true" />
  </property>

  。。。。中间省略了一些

  <property name="status" type="java.lang.String">
  <column name="status" length="1" not-null="true">
  <comment>N-新建, A-已审核, S-暂停, D-已删除</comment>
  </column>
  </property>
  <property name="mapaddress" type="java.lang.String">
  <column name="mapaddress" length="800" />
  </property>
  <set name="shopcoupons" outer-join="true" cascade="none">
  <key column="shopid" foreign-key="shopid"></key>
  <one-to-many class="com.joint.joint_ddw.entity.DdwShopcoupon"/>
  </set>
  </class>
</hibernate-mapping>
-----------------------------------
shopcoupon.hbm.xml
-----------------------------------
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
  Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
  <class name="com.joint.joint_ddw.entity.DdwShopcoupon" table="ddw_shopcoupon" catalog="joint_ddw">
  <id name="couponid" type="java.lang.Integer">
  <column name="couponid" />
  <generator class="native" />
  </id>
  <property name="shopid" type="java.lang.Integer">
  <column name="shopid" not-null="true">
  <comment>0-禮品</comment>
  </column>
  </property>
  。。。中间省略了一些
  <property name="discount" type="java.lang.String">
  <column name="discount" length="3" />
  </property>
  </class>
</hibernate-mapping>
----------------------
shop------------实体类
-------------------------------------------
package com.joint.joint_ddw.entity;

import java.util.HashSet;
import java.util.Set;