Hibernate includes the JPA 2.x API as hibernate-jpa-2.0-api.jar and hibernate-jpa-2.1-api.jar. This makes dependency management in Maven quite hard for larger projects where a simultaneous upgrade is not possible. This is aggravated by the fact that the API packages also include implementation classes in the spi package. Project need to take special care not to include both api jars.

It would be simpler to have a

hibernate-jpa-api.jar with version 2.0.x
and
hibernate-jpa-api.jar with version 2.1.x

In this case, only the most recent jar is choosen.