JPA: NPE when NamingStrategy with xml mapping is used

java.lang.NullPointerException
at org.hibernate.util.StringHelper.unqualify(StringHelper.java:165)
at org.hibernate.cfg.EJB3NamingStrategy.classToTableName(EJB3NamingStrategy.java:40)
at org.jboss.tools.hibernate.jpt.core.internal.context.orm.HibernateOrmTableImpl.buildDefaultDBTableName(HibernateOrmTableImpl.java:78)
at org.jboss.tools.hibernate.jpt.core.internal.context.orm.HibernateOrmTableImpl.synchronizeWithResourceModel(HibernateOrmTableImpl.java:53)
at org.eclipse.jpt.jpa.core.internal.context.orm.AbstractOrmEntity.synchronizeWithResourceModel(AbstractOrmEntity.java:231)
at org.jboss.tools.hibernate.jpt.core.internal.context.orm.HibernateOrmEntityImpl.synchronizeWithResourceModel(HibernateOrmEntityImpl.java:66)
at org.eclipse.jpt.jpa.core.internal.jpa1.context.orm.GenericOrmPersistentType.synchronizeWithResourceModel(GenericOrmPersistentType.java:123)
at org.eclipse.jpt.jpa.core.internal.context.ContextContainerTools.sync(ContextContainerTools.java:137)