@Entity
@Table(name = "users", schema = "public")
public class User implements java.io.Serializable {

   /**
    *
    */
   private static final long serialVersionUID = -2847913650097002280L;
   private Long userId;
   private String username;
   private String passwordHash;
   private String passwordSalt;
   private Merchant merchant;

   @Id
   @SequenceGenerator(name = "user_sequence", sequenceName = "users_user_id_seq")
   @GeneratedValue(strategy=GenerationType.SEQUENCE, generator = "user_sequence")
   @Column(name = "user_id", unique = true, nullable = false)
   public Long getUserId() {
      return this.userId;
   }

   public void setUserId(Long userId) {
      this.userId = userId;
   }

   @Column(name = "username", nullable = false, length = 50)
   public String getUsername() {
      return this.username;
   }

   public void setUsername(String username) {
      this.username = username;
   }

   @Column(name = "password_hash", nullable = false, length = 40)
   public String getPasswordHash() {
      return this.passwordHash;
   }

   public void setPasswordHash(String passwordHash) {
      this.passwordHash = passwordHash;
   }

   @Column(name = "password_salt", nullable = false, length = 8)
   public String getPasswordSalt() {
      return this.passwordSalt;
   }

   public void setPasswordSalt(String passwordSalt) {
      this.passwordSalt = passwordSalt;
   }
   
   @OneToOne(fetch = FetchType.LAZY, mappedBy = "user")
   public Merchant getMerchant() {
      return this.merchant;
   }
   
   public void setMerchant(Merchant merchant) {
      this.merchant = merchant;
   }

}


@Entity
@Table(name = "merchants_tree", schema = "public")
public class MerchantsTree implements java.io.Serializable {

   /**
    *
    */
   private static final long serialVersionUID = 893980006703533469L;
   private Long userIdChildren;
   private User user;
   private Long userIdParent;
   private Integer lft;
   private Integer rgt;

   @GenericGenerator(name = "generator", strategy = "foreign", parameters = @Parameter(name = "property", value = "user"))
   @Id
   @GeneratedValue(generator = "generator")
   @Column(name = "user_id_children", unique = true, nullable = false)
   public Long getUserIdChildren() {
      return this.userIdChildren;
   }

   public void setUserIdChildren(Long userIdChildren) {
      this.userIdChildren = userIdChildren;
   }

   @OneToOne(fetch = FetchType.LAZY)
   @PrimaryKeyJoinColumn
   public User getUser() {
      return this.user;
   }

   public void setUser(User users) {
      this.user = users;
   }

   @Column(name = "user_id_parent")
   public Long getUserIdParent() {
      return this.userIdParent;
   }

   public void setUserIdParent(Long userIdParent) {
      this.userIdParent = userIdParent;
   }

   @Column(name = "lft")
   public Integer getLft() {
      return this.lft;
   }

   public void setLft(Integer lft) {
      this.lft = lft;
   }

   @Column(name = "rgt")
   public Integer getRgt() {
      return this.rgt;
   }

   public void setRgt(Integer rgt) {
      this.rgt = rgt;
   }

}

Criteria criteria = session.createCriteria(MerchantsTree.class);
criteria = criteria.setFetchMode("user", FetchMode.JOIN);
criteria.add(Restrictions.between("lft",  1,18));