When we upgraded Hibernate from 5.2.6 to 5.3.6, we also implicitly upgraded Corda to use JPA 2.2.
corda-core has an explicit dependency on:
but it now also has a transitive dependency on:
These two jars contain nominally the same classes, but Hibernate is expecting the JPA 2.2 jar. This means that the former JPA 2.1 jar should be removed.