JPA 2.1 defines a property to enable schema creation with a persistence provider. According to Steve Ebersole of Hibernate that might conflict with the native schema creation we currently activate in the JpaVendorAdapter implementations (at least for Hibernate). We should make sure that a user does not accidentally activates both.
I'm afraid we have no good way to check for such configuration overlap: A JpaVendorAdapter implementation doesn't have access to the overall JPA configuration, and in the EntityManagerFactoryBean itself, a Hibernate specific check would be a hack.
For that reason, I'd suggest to add a note on this to the reference documentation instead.