Map one object to another object without using foreign key

Hibernate ORM
1

hi, is there any solution to map one object into another object without using foreign key? for example, something like bellow:

@Entity
@Table("tbl_a")
public class A extends BaseEntity {
    
    @Formula("select c.id from tbl_b b, tbl_c c 
               where b.a_id = id 
                 and b.c_id = c.id 
                 and rownum = 1")
    private C c;
}

@Entity
@Table("tbl_b")
public class B extends BaseEntity {

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "a_id")
    private A a;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "c_id")
    private C c;
}

@Entity
@Table("tbl_c")
public class C extends BaseEntity {

    @Column
    private String title;

    @Column
    private String code;
}

note. i don’t wanna to map collection of B in A class. because i need just one row of C class!