JPA @OneToOne Mapping a relationship with ReadOnly Oracle data without primary key

Reference is the owner of the relationship and needs to be specified as such in either a unidirectional or bidirectional relationship

// Unidirection relationship
@Entity
public class Person implements Serializable {
    @Id
    private Long id;
    private String name;
    private String gender;
    // Getters & Setters
}

@Entity
public class Reference implements Serializable {

    @Id
    private String guid;
    private String tableName;

    @OneToOne
    @JoinColumn(name = "sep", insertable = false, updatable = false)
    private Person person;
    //Getters & Setters
}

// Bidirection relationship
@Entity
public class Person implements Serializable {
    @Id
    private Long id;
    private String name;
    private String gender;

    @OneToOne(mappedBy = "person")
    private Reference reference;
    // Getters & Setters
}

@Entity
public class Reference implements Serializable {

    @Id
    private String guid;
    private String tableName;

    @OneToOne
    @JoinColumn(name = "sep", insertable = false, updatable = false)
    private Person person;
    //Getters & Setters
}

Same example for read any kind records from table reference:

@Entity
@Table(name = "reference")
@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
@DiscriminatorColumn(name = "table_name")
public abstract class AbstractReferenceEntity {
    @Id
    private UUID guid;

    public UUID getGuid() {
        return guid;
    }

    public void setGuid(UUID guid) {
        this.guid = guid;
    }
}

@Entity
@DiscriminatorValue("person")
public class PersonReferenceEntity extends AbstractReferenceEntity {
    @OneToOne
    @JoinColumn(name = "sep")
    private Person person;

    public Person getPerson() {
        return person;
    }

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

// Read all types of records.
AbstractReferenceEntity e = this.em.find(AbstractReferenceEntity.class, sameUuid));

// Read only person type of records.
AbstractReferenceEntity e = this.em.find(PersonReferenceEntity, sameUuid);

For the benefit of anyone looking to solve this kind of issue, I will be posting the solution that works for me following @XtremeBaumer suggestion in the comment.

Step 1: For the REFERENCE table, I made the JPA entity to have two ids (sep & table_name) by creating an extra composite Id class and using it in the Reference Entity.

public class RefId {
  private Long sep;
  private String tableName;
  
  //All args constructor
  //No args constructor
  //Setters & Getters
  //Override the equals() and hashCode() !very important
}

Step 2: Add the above class as a composite id to the Reference entity by using the @IdClass annotation. We must also declare and annotate the two fields with @Id in the Reference class.

@Entity
@Table(name="reference")
@IdClass(RefId.class) // Important if not using embeddable type
public class Reference implements Serializable {
  @Id
  private Long sep;
  private String guid;
  @Id
  private String tableName;

  //Getters & Setters
}

Step 3: In the Person entity, declare @OneToOne on the Reference entity and annotate it with @JoinColumnsOrFormulas as shown below:

@Entity
@Table(name="person")
public class Person implements Serializable {
  @Id
  private Long id;
  private String name;
  private String gender;

  @OneToOne
  @JoinColumnsOrFormulas(value = {
    @JoinColumnOrFormula(column = @JoinColumn(name = "id", referencedColumnName = "sep", insertable = false, updatable = false)),
    @JoinColumnOrFormula(formula = @JoinFormula(value = "'person'", referencedColumnName = "tableName"))
  })
  private Reference reference;

 // Getters & Setters
}

This works fine in the scenario above. Note in the formula = @JoinFormula, it is like we are declaring the 'WHERE' clause i.e. WHERE table_name = 'person' (Don't miss the single quotes)

Lastly, by using the Jackson object mapper, I was able to get

{
 "id": 2001, 
 "name": "Moses", 
 "gender": "M", 
 "reference": {
   "sep": 2001, 
   "guid": "EA48-...",
   "tableName": "person"
 }
}

Thanks for your insight (@XtremeBaumer)