No se que "documentación" consultaste, pero la JAvadoc de Hibernate es esta y está bastante claro.
Cita: buildSessionFactory
public SessionFactory buildSessionFactory()
throws HibernateException
Deprecated. Use buildSessionFactory(ServiceRegistry) instead
Create a SessionFactory using the properties and mappings in this configuration. The SessionFactory will be immutable, so changes made to this Configuration after building the SessionFactory will not affect it.
Returns:
The build SessionFactory
Throws:
HibernateException - usually indicates an invalid configuration or invalid mapping information