@Entity
@Table(name = "Contacts")
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name = "discriminator", discriminatorType = DiscriminatorType.STRING)
public abstract class Contact implements Serializable
{
	@Id
	@Column(name = "id")
	private Integer id;

	...
}

@Entity
@Table(name = "Persons")
@DiscriminatorValue(value = "person")
public class Person extends Contact implements Serializable
{
	@Column(name = "first_name")
	private String firstName;

	@Column(name = "last_name")
	private String lastName;

	...
}

@Entity
@Table(name = "Players")
public class Player extends Person implements Serializable
{
	@Column(name = "registration_nbr")
	private String registrationNbr = null;

	...
}

// returns Person instance -> correct
Contact co = em.find(Contact.class, 1);
System.out.println("Loaded contact = " + co + "</p><p>");

// returns Person instance -> correct
Person pe = em.find(Person.class, 1);
System.out.println("Loaded person = " + pe + "</p><p>");

// returns Person instance -> wrong (ClassCastException)
Player pl = em.find(Player.class, 1);
System.out.println("Loaded player = " + pl + "</p><p>");

Loaded contact = tld.persons.model.Person@7f636e4e[id=1,firstName=Michael,lastName=Jordan]
Loaded person = tld.persons.model.Person@7f636e4e[id=1,firstName=Michael,lastName=Jordan]

Exception in thread "main" java.lang.ClassCastException: tld.persons.model.Person cannot be cast to tld.persons.model.Player
    at tld.persons.Main.main(Main.java:82)

current class = requested class

while current class is abstract
{
	// return nearest instantiable sub entity
	
	if discriminator on current class
	{
		// follow non-ambiguous path... continue
		current class = discriminator sub class
	}
	else
	{
		// possibly ambiguous!
		return null
		
		// or alternatively, find a lone sub entity in any of the subs
	}
}


if entity found of type current class
{
	return entity
}
else
{
	return null
}

Player pl1 = em.find(Player.class, 1);