Hibernate version:
3.x
Mapping documents:

<class name = "com.jd.hibernate.associations.Conference" table = "TEST_JD_CONFERENCE" >
<id name = "conf_Id" column = "conf_Id"> <generator class = "identity"/>
</id>
<property name = "name" column = "Name" type
= "java.lang.String" /> ...<!--other props-->..

<list name = "usersInConference"inverse="true" cascade = "save-update">
<key column="conf_Id" />
<list-index column="idx"></list-index>
<one-to-many class = "com.jd.hibernate.associations.Users" />
</list>
</class>

<class name = "com.jd.hibernate.associations.Users" table = "TEST_JD_USERS" discriminator-value="Users">
<id name = "id" column = "ID" type = "int">
<generator class = "increment"/>
</id>
<discriminator column = "Users_Type" type = "java.lang.String" />
<property name = "userType" type = "java.lang.String" column = "USERTYPE" />
..<!-- other properties --> ..
<component name="conference" class = "com.jd.hibernate.associations.Conference" >
<!-- mapping necessary only for the required attributes that will be saved along with this -->
<property name = "name" column = "Name" type = "java.lang.String" />
<property name = "desc" column = "Description" type = "java.lang.String" />
<property name = "startDate" column = "StartDate" type = "date" />
<property name = "endDate" column = "EndDate" type = "date" />
</component>
</class>


Code between sessionFactory.openSession() and session.close():

tx.begin();
Conference conf = new Conference();
Users users = new Users();
Users users1 = new Users();
List userList = new ArrayList(); users.setEmail("test@asd.com"); users.setFirtName("navnith"); users.setHomePhone(342); users.setLastName("M"); users.setPassword("navnith"); users.setUserType("S"); users.setWorkPhone(3214); users1.setEmail("test1@asd.com"); users1.setFirtName("11n1avnith"); users1.setHomePhone(11342); users1.setLastName("11M"); users1.setPassword("11navnith"); users1.setUserType("11S"); users1.setWorkPhone(11214); conf.setDesc("usersconfdesc"); conf.setEndDate(new Date(1,1,1)); conf.setName("Test for users"); conf.setStartDate(new Date()); users.setConference(conf); users1.setConference(conf); userList.add(users);
userList.add(users1); conf.setUsersInConference(userList); session.save(conf);


Full stack trace of any exception that occurs:

Name and version of the database you are using:
MS SQL

Now, the Conf_id and the idx columns are being updated as null and .. I have no clue why. Any pointers on what wrong I am doing ?

Rgds