When I load in an enity called group from a session as shown in the code below (which also apperently loads in the GroupUsers associated with that group as can be seen from the SQL below, also see the hibernate mapping), then perform some updates and then call this code again for the second time to see my changes, I am not getting the groupUsers the way they now appear in the database, but rather a cached version from the last time the code was called. As soon as I do a page refresh, I get the right data. Now, the SQL is being regenerated, I checked. So it would appear that it's the outcome of the query that's being cached, but I am not an expert.

Hibernate version:
2.1.8

Mapping documents:

hibernate.cfg.xml

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
"-//Hibernate/Hibernate Configuration DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-configuration-2.0.dtd">

<!-- This is a generated file that is synchronized -->
<!-- by MyEclipse Hibernate tool integration. -->
<hibernate-configuration>

<session-factory>
<!-- properties -->
<property name="connection.username">root</property>
<property name="connection.url">jdbc:mysql://localhost:3306/workflow</property>
<property name="dialect">net.sf.hibernate.dialect.MySQLDialect</property>
<property name="connection.password">blah</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
<property name="show_sql">true</property>
<!-- mapping files -->
<mapping resource="com/talisen/workflow/hibernate/Group.hbm.xml"/>
<mapping resource="com/talisen/workflow/hibernate/User.hbm.xml"/>
<mapping resource="com/talisen/workflow/hibernate/GroupUser.hbm.xml"/>
</session-factory>

</hibernate-configuration>

Group.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
<!--
Based on the Mapping file for the Category class of CaveatEmptor.
-->
<hibernate-mapping package="com.talisen.workflow.hibernate">

<class name="Group" table="GROUPYO">
<!-- Common id property. -->
<id name="groupId" type="java.lang.Integer" column="GROUP_ID"
unsaved-value="null">
<generator class="native" />
</id>
<property name="groupName" type="java.lang.String">
<column name="GROUP_NAME" not-null="true"
unique-key="UNIQUE_NAME_AT_LEVEL" />
</property>
<property name="groupDesc" column="GROUP_DESC"
type="java.lang.String" not-null="false" />

<set name="groupUsers" inverse="true" cascade="none"
order-by="STATUS_ID">
<key column="GROUP_ID" />
<one-to-many
class="com.talisen.workflow.hibernate.GroupUser" />
</set>
</class>

</hibernate-mapping>

User.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
<!--
Based on the Mapping file for the Item class of CaveatEmptor.
-->
<hibernate-mapping package="com.talisen.workflow.hibernate">

<class name="User" table="USER">

<!-- Common id property. -->
<id name="userId" type="java.lang.Integer" column="USER_ID"
unsaved-value="null">
<generator class="native" />
</id>

<!-- Name of the item is immutable. -->
<property name="userName" type="java.lang.String"
column="USER_NAME" not-null="true" />

<set name="groupUsers" inverse="true" cascade="none"
order-by="STATUS_ID">
<key column="USER_ID" />
<one-to-many
class="com.talisen.workflow.hibernate.GroupUser" />
</set>
</class>
</hibernate-mapping>

GroupUser.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
<hibernate-mapping package="com.talisen.workflow.hibernate">
<!--Based on the mapping file for the CategorizedItem class of CaveatEmptor. -->

<class name="GroupUser" table="USER_GROUP">

<composite-id name="groupUserKey" class="GroupUser$Id"
unsaved-value="any">
<key-property name="groupId" access="field"
column="GROUP_ID" />

<key-property name="userId" access="field"
column="USER_ID" />
</composite-id>
<many-to-one name="group" insert="false" update="false"
not-null="true" column="GROUP_ID" />

<many-to-one name="user" insert="false" update="false"
not-null="true" column="USER_ID" />
</class>
</hibernate-mapping>

Code between sessionFactory.openSession() and session.close():
session = SessionFactory.currentSession();
Transaction tx = session.beginTransaction();
group = (Group) session.load(Group.class, groupId);
tx.commit();

Name and version of the database you are using:
MySQL 4.1.8-nt

The generated SQL (show_sql=true):
Hibernate: select group0_.GROUP_ID as GROUP_ID0_, group0_.GROUP_NAME as GROUP_NAME0_, group0_.GROUP_DESC as GROUP_DESC0_ from GROUPYO group0_ where group0_.GROUP_ID=?

Hibernate: select groupusers0_.GROUP_ID as GROUP_ID__, groupusers0_.USER_ID as USER_ID__, groupusers0_.GROUP_ID as GROUP_ID1_, groupusers0_.USER_ID as USER_ID1_, user1_.USER_ID as USER_ID0_, user1_.USER_NAME as USER_NAME0_ from USER_GROUP groupusers0_ left outer join USER user1_ on groupusers0_.USER_ID=user1_.USER_ID where groupusers0_.GROUP_ID=? order by groupusers0_.STATUS_ID

Hibernate: select groupusers0_.USER_ID as USER_ID__, groupusers0_.GROUP_ID as GROUP_ID__, groupusers0_.GROUP_ID as GROUP_ID1_, groupusers0_.USER_ID as USER_ID1_, group1_.GROUP_ID as GROUP_ID0_, group1_.GROUP_NAME as GROUP_NAME0_, group1_.GROUP_DESC as GROUP_DESC0_ from USER_GROUP groupusers0_ left outer join GROUPYO group1_ on groupusers0_.GROUP_ID=group1_.GROUP_ID where groupusers0_.USER_ID=? order by groupusers0_.STATUS_ID