NIFI-9292: Added getInputPortNames() and getOutputPortNames() to Stat…

[markap14]

…elessDataflowDefinition and getReadOnlyExtensionsDirectories() to StatelessEngineConfiguration

• Addressed issue identified in system test where a flow can fail due to FailurePortEncounteredException but then purge the flow in the background after the call to trigger completes

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Enables X functionality; fixes bug NIFI-YYYY.

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[gresockj]

These look like some sensible improvements that will allow the Stateless API to be used more flexibly. I have one comment about possibly providing a built-in implementation of the new #getReadOnlyExtensionsDirectories(), but otherwise it looks good.

[gresockj]

I understand that code outside of the Stateless framework could choose to implement a StatelessEngineConfiguration that provides this value, but perhaps it would be worth adding support for it in this class as well. What do you think? And if so, the documentation should also be updated.

[markap14]

Oops. Yes, that should definitely be there. Will update.

[gresockj]

I also ran Stateless with this PR and observed the new log statements, which would help in detecting classpath issues:

2021-10-17 07:39:42,460 INFO [main] o.a.n.s.bootstrap.StatelessBootstrap Creating Stateless Bootstrap with the following URLs in the classpath:
2021-10-17 07:39:42,461 INFO [main] o.a.n.s.bootstrap.StatelessBootstrap Additionally, Root ClassLoader has the following URLs available:

The Stateless dataflows I ran all succeeded with this PR.

[gresockj]

Changes look good -- I was able to use the new property in my stateless.properties configuration. I'll merge once the ci-workflow checks complete.

[gresockj]

Merging!