@Entity
@Table(uniqueConstraints = {@UniqueConstraint(columnNames = {"groupName"})})
public class UserGroup extends BusinessObject {
   private String groupName;
   private UserGroup parent;
   private List<UserGroup> children;
   private List<User> users;
   
   @Column(length=50, nullable=false)
   public String getGroupName() {
      return groupName;
   }
   public void setGroupName(String groupName) {
      this.groupName = groupName;
   }
   
   @ManyToOne
   public UserGroup getParent() {
      return parent;
   }
   public void setParent(UserGroup parent) {
      this.parent = parent;
   }
   
   @OneToMany(mappedBy="parent")
   @Cascade ({CascadeType.SAVE_UPDATE})
   @OrderBy("groupName")
   public List<UserGroup> getChildren() {
      if(null == this.children){
         this.children = new LinkedList<UserGroup>();
      }
      return children;
   }
   public void setChildren(List<UserGroup> children) {
      this.children = children;
   }
   public void addChild(UserGroup userGroup){
      this.getChildren().add(userGroup);
      userGroup.setParent(this);
   }
   
   @OneToMany(mappedBy="userGroup")
   @Cascade ({CascadeType.SAVE_UPDATE})
   public List<User> getUsers() {
      if(null == this.users){
         return new LinkedList<User>();
      }
      return users;
   }
   public void setUsers(List<User> users) {
      this.users = users;
   }
   public void addUser(User user){
      this.getUsers().add(user);
      user.setUserGroup(this);
   }
   
   @Transient
   public boolean isRoot(){
      return null == this.getParent();
   }
   
   public void initialize(){
      if(getChildren() != null){
         Hibernate.initialize(getChildren());
      }
   }
}

public class UserGroupListController extends GenericSingleViewController {
   private SecurityService securityService;

    public SecurityService getSecurityService() {
      return securityService;
   }

   public void setSecurityService(SecurityService securityService) {
      this.securityService = securityService;
   }
   
   @Override
   protected ModelAndView handleRequestInternal(HttpServletRequest request,
         HttpServletResponse response) throws Exception {
      ModelAndView resultPage = new ModelAndView(getViewPage());
      UserGroup userGroup = securityService.getUserGroup(new Long(1));
      logger.debug("is Open --> ", Hibernate.isInitialized(userGroup.getChildren()));
      userGroup.initialize();
      resultPage.addObject("root", userGroup);
      return resultPage;
   }
}

<%@ include file="/WEB-INF/tags/tags.inc"%>

<layout:mainLayout pageTitle="">
   <layout:leftContent  title="User Group List" collapsible="false">
      <div id="tree" style="margin-top: 10px;"></div>
   </layout:leftContent>
   <layout:mainContent>
      <c:if test="${!empty root}">
         <c:forEach var="child" items="${root.children}">
            <p>${child.groupName}</p>
         </c:forEach>
      </c:if>
   </layout:mainContent>
</layout:mainLayout>