My exam cloud mock 4, primary key class

[Himai Minh]

The Java Persistence entity UserRole defines a composite primary key that is defined by the two columns userID and RoleID in the DB.
Which two are true?
Choose two.
A. UserRole must define a primary key class to represent the composite primary key.
B. The composite primary key is mapped as two fields in UserRole. No extra primary key class is necessary.
C. The combination of @Embedded and @Embeddable annotations can be used to denote the composite primary key.
D. The semantics of the equals and hashCode methods of the primary key class must be consist with the database equality.
Given answers :A,D.

I think the answers should be A,B,D.
For example, the two id's field should be mapped to the columns

@IdClass(Id.class)
@Entity
public class UserRole{
@Id
@Column(name="UserID")
private int id;

@Id
@Column(name="RoleID")
private int userRoleId;
}

public class Id implements Serializable{
private int id;
private int userRoleId;
}

[Frits Walraven]

B is not correct because you need an extra primary key class (the one you are showing: @IdClass(Id.class))