@Entity
public class Employee {
   private static final long serialVersionUID = 1L;

   @Id
   @Column(name="EMP_ID")
   private Long empId;

   @Column(name="EMP_NAME")
   private String empName;

   //bi-directional many-to-one association to EmployeeDtl
   @OneToMany(mappedBy="employee", cascade=CascadeType.ALL, fetch=FetchType.EAGER)
   private Set<EmployeeDtl> empDtls;

@Entity
@Table(name="EMP_DTL")
public class EmployeeDtl {

   @Id
   @Column(name="EMP_DTL_ID")
   private Long empDtlId;

   @Column(name="EMP_GRP")
   private String employeeGrp;


   //bi-directional many-to-one association to Employee
    @ManyToOne
   @JoinColumn(name="EMP_ID")
   private Employee employee;
   
    @Column(name="EMP_ID", insertable=false, updatable=false)
   private Long empId;

   //bi-directional many-to-one association to EmpDeptDtl
   @OneToMany(mappedBy="id.empDtlId", cascade= CascadeType.ALL)
   private Set<EmpDeptDtl> empDeptDtls;

@Entity
public class EmpDeptDtl {

   @EmbeddedId
   private EmpDeptDtlPK id;

   @Column(name="EMP_DTL_ID", insertable = false, updatable = false)
   private Long empDtlId;
   
   //bi-directional many-to-one association to Dept
    @ManyToOne(fetch=FetchType.LAZY)
   @JoinColumn(name="DEPT_ID", insertable = false, updatable = false)
   private Dept deptId;

@Embeddable
public class EmpDeptDtlPK implements Serializable {
   //default serial version id, required for serializable classes.
   private static final long serialVersionUID = 1L;

   @Column(name="DEPT_ID")
   private Long deptId;

   //bi-directional many-to-one association to EmpDeptDtl
    @ManyToOne(fetch=FetchType.LAZY)
   @JoinColumn(name="EMP_DTL_ID")
   private EmployeeDtl employeeDtl;

@Entity
public class Dept  {

   @Id
   @Column(name = "DEPT_ID")
   private Long deptId;

   @Column(name = "DEPT_NAME")
   private String deptName;

        // bi-directional many-to-one association to EmpDeptDtl
   @OneToMany(mappedBy = "deptId")
   private Set<EmpDeptDtl> empDeptDtls;