NIFI-9677 Fixed LookupRecord issue that an empty JSON array caused mismatch

[jrsteinebrey]

Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

• Pull Request title starts with Apache NiFi Jira issue number, such as NIFI-00000
• Pull Request commit message starts with Apache NiFi Jira issue number, as such NIFI-00000

Pull Request Formatting

• Pull Request based on current revision of the main branch
• Pull Request refers to a feature branch with one commit containing changes

Verification

I added two new unit tests to verify my fix.
I also manually tested the new code works as intended in a local build of NiFi editor.

Build

• Build completed using mvn clean install -P contrib-check
  • JDK 21

Licensing

N/A

Documentation

N/A

[mattyb149]

Reviewing...

[mattyb149]

When running the unit tests with Java 8 (for a support/nifi-1.x backport), I get an error because the foo entry shows up as null in the output of testLookupMissingJsonField():

[{"foo":null,"unmentioned":{"foo":"original"}}]

I checked some commits and everything looks the same, but I'm guessing there was some change made to the record-based stuff in main that didn't make its way back to the 1.x branch. Either way JSON is not guaranteed to have "ordered" fields, so we should figure out why the "foo": null is in there (if it shouldn't be) or check each field for its contents rather than the whole output FlowFile.

[mattyb149]

+1 LGTM, thanks for the fix! Merging to support/nifi-1.x and main