@Entity
@Table(name="datasource")
public class DatasourceDom implements Serializable {

@Id
@Column(name = "id")   
private int id;

@Column(name = "alias")
private String alias;   

@Column(name = "url")
private String url;


@Entity
@Table(name = "ds_restriction")
public class DsRestrictionDom implements Serializable {

@Id
@Column(name = "datasource_id")
private int datasourceId;

@Id
@Column(name = "principal")
private String principal;   

@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "datasource_id")
private DatasourceDom datasource;

public List<DsRestrictionDom> getDatasorcesRestictions() {
    Session session = getCurrentSession();
    Criteria criteria = session.createCriteria(DsRestrictionDom.class);
    criteria.createCriteria("datasource","ds",JoinType.RIGHT_OUTER_JOIN);
    List<DsRestrictionDom> dsList = criteria.list();       
    return dsList;
}

[
  null,
  null,
  null,
  null,
  null,
  null,
  null,
  {
    "datasourceId": 1,
    "principal": "PUBLIC",   
    "datasource": {
      "id": 1,
      "alias": "alias1",     
      "url": "some url"
    }
  },
  null,
  null
]

@Entity
@Table(name="datasource")
public class DatasourceDom implements Serializable {

    @Id
    @Column(name = "id")
    private int id;

    @Column(name = "alias")
    private String alias;

    @Column(name = "url")
    private String url;
   
    @OneToMany(mappedBy = "datasource", cascade = CascadeType.ALL)
    private List<DsRestrictionDom> dsRestrictionDoms = new ArrayList<>();

    ...
}

select dd
from DatasourceDom dd
left join fetch dd.dsRestrictionDoms