FKI used to be persisted in datastore to help speed up loading by foreign key.
Now it is just a helper class to do the same thing in SQL because
indexing is natively supported in SQL.
* Upgradle JUnit to 4.13
Removed third_party/junit folder and all usage of the
JunitBackPort class. As a result, third_party is no
longer a Gradle subproject.
Minor code changes were needed to work around an
error-prone pattern: multiple statement in assertThrows'
runnable lambda.
Also third_party/activation and third_party/jsch. These
dependencies are loaded from remote maven repo. The local
copies are not in use.
