The problem is in SessionFactoryImpl, the creation of a new SchemaExport is done in thte constructor of SessioFactoryImpl when the hbm2ddl property is set. The schema export fails because it runs org.hibernate.cfg.Configuration.generateSchemaCreationScript(...) and it cannot recognize some types. This is the error:

javax.persistence.PersistenceException: [PersistenceUnit: jpajtastandalone] Unable to build Hibernate SessionFactoryCaused by: org.hibernate.MappingException: No Dialect mapping for JDBC type: -2

I've tried to override the methods in OgmConfiguration but I still have the error if Persistence.createEntityManagerFactory(...) is used.