When filling a collection with a subselect using Postgres (any version?) Postgres complains missing a compulsory alias of the subselect in the FROM.

NOW:
select count(tipoRelacion) from ( <subselect> ) where recepcion_id =?
Needed:
select count(tipoRelacion) from ( <subselect> ) as t where recepcion_id =?

This is exclusive to Postgres. Hibernate only has to add an as alias

The Hibernate error:
{{
Hibernate: select count(tipoRelacion) from ( select r1.recepcion_id,r1.tfd_uuid, rel.tipoRelacion, r2.tfd_uuid as rel_uuid, rel.rel_uuid as uuid, r2.recepcion_id as r2
from recepcion_cfdi as r1
join recepcion_cfdi_rel as rel on (r1.tfd_uuid=rel.rel_uuid)
join recepcion_cfdi as r2 on (rel.recepcion_id = r2.recepcion_id)
) where recepcion_id =?
2018-05-16 12:22:45.001 [ajp-nio-8009-exec-1] WARN org.hibernate.engine.jdbc.spi.SqlExceptionHelper - SQL Error: 0, SQLState: 42601
2018-05-16 12:22:45.002 [ajp-nio-8009-exec-1] ERROR org.hibernate.engine.jdbc.spi.SqlExceptionHelper - ERROR: subquery in FROM must have an alias
Hint: For example, FROM (SELECT ...) [AS] foo.
Position: 33}}

The mapping follows:

{{<hibernate-mapping package="com.fcm.cfdi.recepcion" schema="public">
<class name="Recepcion" entity-name="Recepcion" table="recepcion_cfdi" >
<id name="id" column="recepcion_ID">
<generator class="native"/>
</id>
...
<set name="relacionadosIn" lazy="extra" cascade="none" >
<subselect>select r1.recepcion_id,r1.tfd_uuid, rel.tipoRelacion, r2.tfd_uuid as rel_uuid, rel.rel_uuid as uuid, r2.recepcion_id as r2
from recepcion_cfdi as r1
join recepcion_cfdi_rel as rel on (r1.tfd_uuid=rel.rel_uuid)
join recepcion_cfdi as r2 on (rel.recepcion_id = r2.recepcion_id)
</subselect>
<synchronize table="recepcion_cfdi_rel"/>
<key column="recepcion_id" not-null="true" update="false"/>
<composite-element class="RecepcionRelacion">
<property name="tipoRelacion" not-null="true" length="2"/>
</composite-element>
</set>

</class>
</hibernate-mapping>
}}

I'm trying to make a test version, so you can reproduce the issue.