@Entity
public Person
{
  private Student student;
   
  @OneToOne(cascade = CascadeType.ALL, fetch = FetchType.LAZY,  optional = true)
  @JoinColumn(name = "person_id")
  public Student getStudent() {
    return student;
  }
  public void setStudent(Student student) {
    this.student = student;
  }
}

@Entity
public Student
{
    private Person person;

    @OneToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "person_id")   
    public Person getPerson()
    {
        return person;
    }

    public void setPerson(Person person)
    {
        this.person = person;
    }
}