@Entity
@Table(name="form")
public class Form implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    @JsonView(EntityView.SummaryView.class)
    private Long id;

    @JsonView(EntityView.SummaryView.class)
    private String name;

    @JsonView(EntityView.DetailView.class)
    @OneToMany(mappedBy = "form", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    private List<FormLabel> labels;
}

@Entity
@Table(name="form_label")
public class FormLabel implements Serializable {

    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    @JsonView(EntityView.SummaryView.class)
    private Long id;

    @ManyToOne
    @JoinColumn(name = "form_id")
    @JsonIgnore
    private Form form;

    @JsonView(EntityView.SummaryView.class)
    private String lang;

    @JsonView(EntityView.SummaryView.class)
    private String value;
}

select form0_.id as id1_0_, form0_.name as name2_0_ , coalesce(labels1_.value,labels2_.value)
from form form0_
left outer join form_label labels1_ on form0_.id=labels1_.form_id and (labels1_.lang='pt')
left outer join form_label labels2_ on form0_.id=labels2_.form_id and (labels2_.lang='en')
where form0_.name='Form 1'

QForm form = QForm.form;
QFormLabel requestedLabels =new QFormLabel("requestedLabels");
QFormLabel defaultLabels  = new QFormLabel("defaultLabels");
Form f = new JPAQuery<Form>(entityManager).from(form)
    .leftJoin(form.labels, requestedLabels)
    .on(requestedLabels.lang.eq(localeRequested.getLanguage()))
    .leftJoin(form.labels, defaultLabels)
    .on(defaultLabels.lang.eq(localeDefault.getLanguage()))
    .where(QForm.form.name.eq(name)).fetchOne();

f = (Form) q.from(form)
.leftJoin(form.labels, requestedLabels)
//.on(labels.lang.eq(locale.getLanguage())/* .and(form.id.eq(labels.form.id)) */)
.fetchJoin()
.where(QForm.form.name.eq(name).and(requestedLabels.lang.eq(localeRequested.getLanguage()))).fetchFirst();