TESTCLASSB1(
  "IDTESTB1" NUMBER(19,0) NOT NULL ENABLE, 
  "FIELDX" VARCHAR2(255 BYTE), 
  "FIELDY" VARCHAR2(255 BYTE), 
  PRIMARY KEY ("IDTESTB1")
)
with only one row with values (1,null,null)

TESTCLASSB2(
  "IDTESTB2" NUMBER(19,0) NOT NULL ENABLE, 
  "FIELDX" VARCHAR2(255 BYTE), 
  "FIELDY" VARCHAR2(255 BYTE), 
  PRIMARY KEY ("IDTESTB2")
)
with only one row with values (1,null,null)

TESTCLASSA(
  "IDTESTA" NUMBER(19,0) NOT NULL ENABLE, 
  "IDTESTB1" NUMBER(19,0), 
  "IDTESTB2" NUMBER(19,0), 
  PRIMARY KEY ("IDTESTA")
)
with only one row with values (1,1,1)

@Entity
@Table
public class TestClassB1 {
    @Id
    public Long idTestB1;  
    
    public String fieldX; 
    
    @Basic(fetch= FetchType.LAZY)
    public String fieldY;
    
    public TestClassB1(){
        super();
    }
}

@Entity
@Table
public class TestClassB2 {
    @Id
    public Long idTestB2;  
    
    public String fieldX; 
    
    @Basic(fetch= FetchType.LAZY)
    public String fieldY;
    
    public TestClassB2(){
        super();
    }
}

@Entity
@Table
public class TestClassA {
    @Id
    public  Long idTestA;
    
    @ManyToOne
    @JoinColumn(name = "IDTESTB1")
    public TestClassB1 b1;
    
    @ManyToOne
    @JoinColumn(name = "IDTESTB2")
    public TestClassB2 b2;
    
    public TestClassA() {
        super();
    }
}

  <persistence-unit name="testPU" transaction-type="RESOURCE_LOCAL">
    <provider>org.eclipse.persistence.jpa.PersistenceProvider</provider>
    <non-jta-data-source>java:/app/jdbc/testDS</non-jta-data-source>
    
    <exclude-unlisted-classes>false</exclude-unlisted-classes>
    
    <properties>
       <property name="eclipselink.target-server" value="WebLogic_10" />
       <property name="eclipselink.logging.level" value="WARNING"/>
       <property name="eclipselink.logging.level.sql" value="FINE"/>                    
    </properties>

  </persistence-unit>

        Long idTestA = 1L;
        
        EntityManagerFactory factory = Persistence.createEntityManagerFactory("testPU");
        EntityManager em =  factory.createEntityManager();        
        
        TestClassA a = em.find(TestClassA.class, idTestA);
        
        CriteriaBuilder cb = em.getCriteriaBuilder();
                
        CriteriaQuery<TestClassA> query = cb.createQuery(TestClassA.class);        
        Root<TestClassA> aFrom = query.from(TestClassA.class);
                        
        Fetch<TestClassA, TestClassB1> fetchAa = aFrom.fetch(TestClassA_.b1);                        
        Fetch<TestClassA, TestClassB2> fetchAb = aFrom.fetch(TestClassA_.b2);
                
        query.select(aFrom);
        query.where(cb.equal(aFrom.get(TestClassA_.idTestA),idTestA));
        
        TypedQuery<TestClassA> tq = em.createQuery(query); 
        
        tq.setFirstResult(0);
        tq.setMaxResults(10);
        
        List<TestClassA> listTestA = tq.getResultList();
        
        em.close();
        factory.close();

javax.persistence.PersistenceException: Exception [EclipseLink-4002] (Eclipse Persistence Services - 2.5.1.v20130918-f2b9fc5): org.eclipse.persistence.exceptions.DatabaseException
Internal Exception: java.sql.SQLSyntaxErrorException: ORA-00918: columna definida de forma ambigua

Error Code: 918
Call: SELECT * FROM (SELECT a.*, ROWNUM rnum  FROM (SELECT t1.IDTESTA AS a1, t1.IDTESTB1 AS a2, t1.IDTESTB2 AS a3, t0.IDTESTB1, t0.FIELDX, t2.IDTESTB2, t2.FIELDX FROM TESTCLASSB1 t0, TESTCLASSB2 t2, TESTCLASSA t1 WHERE ((t1.IDTESTA = ?) AND ((t0.IDTESTB1 = t1.IDTESTB1) AND (t2.IDTESTB2 = t1.IDTESTB2)))) a WHERE ROWNUM <= ?) WHERE rnum > ?
        bind => [1, 10, 0]
Query: ReadAllQuery(referenceClass=TestClassA sql="SELECT * FROM (SELECT a.*, ROWNUM rnum  FROM (SELECT t1.IDTESTA AS a1, t1.IDTESTB1 AS a2, t1.IDTESTB2 AS a3, t0.IDTESTB1, t0.FIELDX, t2.IDTESTB2, t2.FIELDX FROM TESTCLASSB1 t0, TESTCLASSB2 t2, TESTCLASSA t1 WHERE ((t1.IDTESTA = ?) AND ((t0.IDTESTB1 = t1.IDTESTB1) AND (t2.IDTESTB2 = t1.IDTESTB2)))) a WHERE ROWNUM <= ?) WHERE rnum > ?")
        at org.eclipse.persistence.internal.jpa.QueryImpl.getDetailedException(QueryImpl.java:378)
        at org.eclipse.persistence.internal.jpa.QueryImpl.executeReadQuery(QueryImpl.java:260)
        at org.eclipse.persistence.internal.jpa.QueryImpl.getResultList(QueryImpl.java:469)
        at TestServlet.test1(TestServlet.java:109)
        at TestServlet.service(TestServlet.java:45)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
        at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227)
        at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125)
        at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:300)