I have found it in the the 5.0.0.CR3
http://grepcode.com/file/repo1.maven.org/maven2/org.hibernate/hibernate-entitymanager/5.0.0.CR3/org/hibernate/jpa/spi/AbstractEntityManagerImpl.java#AbstractEntityManagerImpl

It seems this org.hibernate.ejb.AbstractEntityManagerImpl was deprecated and replaced by the org.hibernate.jpa.spi.AbstractEntityManagerImpl

in the above link the line 1682 to 1690 still the same issue or lack of high lightning of the cause.

Hope this could help

Regards,
Alan Mehio
London