Of course I found several posts that say this is because I have persistence-api-1.0.jar somewhere in my classpath somewhere, but I don't (at least I can't find it )
I also read that this a symptom of not having a JPA 2 enabled web server, but I'm just running a unit test here.
I read that I need a jpa2 jar and I downloaded the Geronimo one ( geronimo-jpa_2.0_spec-1.0-PFD2.jar ) that definitely has the orphanRemoval() method but I'm still getting the error, which means that some other jar is providing the OneToMany class.
I can't find that other jar!
I'm running this from intelliJ IDEA
Here is a list of all the jars on my classpath: