...
@Entity
@Table(name="A")
public class A
{
   
    @Id
    @GeneratedValue(generator="SEQ_FELLES")
    @SequenceGenerator(name="SEQ_FELLES", sequenceName="ODB_FELLES_SEQ", allocationSize=1)
    @Column(name="A_ID")
    private long id;

    @OneToMany(mappedBy="A", fetch=FetchType.EAGER)
    private Set<AX> setOfAX;
...
}

@Entity
@Table(name="AX")
public class AX
{
    @Id
    @GeneratedValue(generator="SEQ_FELLES")
    @SequenceGenerator(name="SEQ_FELLES", sequenceName="ODB_FELLES_SEQ", allocationSize=1)
    @Column(name="AX_ID")
    private long id;
   
    @ManyToOne
    @JoinColumn(name="A_ID")
    private A aAObj;
   
    @ManyToOne
    @JoinColumn(name="C_ID")
    private C aCObj;

    @Column(name="SOME_VALUE")
    private long someValue;
...
}

@Entity
@Table(name="C")
public class C
{   
    @Id
    @Column(name="C_ID")
    private long cId;

    @Column(name="ANOTHER_VALUE")
    private long anotherValue;
...
}