Fast Object Database for Java - with JPA/JDO support

unwrap(cls) - JPA EntityManager's method

Return an object of the specified type to allow access to the provider-specific API. If the provider's EntityManager implementation does not support the specified class, the PersistenceException is thrown.
cls - the class of the object to be returned. This is normally either the underlying EntityManager implementation class or an interface that it implements.
an instance of the specified class
PersistenceException - if the provider does not support the call
JPA 2.0