Fail after exceptions from ValidationTasks

[mikejritter]

JIRA Ticket: https://fedora-repository.atlassian.net/browse/FCREPO-3811

What does this Pull Request do?

Stops execution of validation tasks when exceptions occur in the tasks which are unhandled.

What's new?

• Add flag for signaling abort in the ValidationExecutionManager
• Create ValidationTasks as CompletableFutures for better exception handling
• Add test which throws a RuntimeException when writing ValidationResults
• Typos/import updates

How should this be tested?

The best way to test this is to have the ValidationResultWriter fail, which can be done by specifying a --results-dir which cannot be written, e.g.:

java -jar target/fcrepo-migration-validator-1.2.0-SNAPSHOT-driver.jar -c /data/migration/f6-migration/data/ocfl-root -d /data/migration/f3dataset/2018/datastreams -o /data/migration/f3dataset/2018/objects -s legacy -r /reports -R csv

Additional Notes

I also opted to not attempt to write reports if any exceptions occurred from the ValidationExecutionManager. Since the only exception we re-throw is the RuntimeException in the FileSystemValidationResultWriter, I felt it was safe to do so as we wouldn't be able to write any of the reports.

Interested parties

Tag (@ mention) interested parties or, if unsure, @fcrepo/committers

[dbernstein]

Looks good. Thanks @mikejritter