NIFI-7686: Support multiple key columns in database lookup services

[lhapollo]

Summary

NIFI-7686

Added composite key support to DatabaseRecordLookupService and SimpleDatabaseLookupService. When LOOKUP_KEY_COLUMN contains a comma-separated list of column names, the services build a composite WHERE clause and expect coordinates keyed by column name instead of the single 'key' coordinate.

Includes type coercion so String values from LookupRecord are converted to the correct SQL types based on ParameterMetaData.

Backward compatible: single-key behavior is unchanged.

Tracking

Please complete the following tracking steps prior to pull request creation.

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

Please indicate the verification steps performed prior to pull request creation.

Build

• Build completed using ./mvnw clean install -P contrib-check
  • JDK 21
  • JDK 25

Licensing

• New dependencies are compatible with the Apache License 2.0 according to the License Policy
• New dependencies are documented in applicable LICENSE and NOTICE files

Documentation

• Documentation formatting appears as expected in rendered files

[dan-s1]

@lhapollo Please note the merge is blocked as the commits must have verified signatures. Please see here for creating commits with verified signatures

[dan-s1]

@lhapollo It looks like there are Checkstyle and PMD violations in the two builds that are failing. Please correct those.

[exceptionfactory]

Thanks for proposing this new feature @lhapollo. On initial review, this change introduces notable behavior changes, and has duplicative logic for things like coercing values. Expanding the semantic behavior of the Lookup Key Column property is also potentially confusing, so at minimum, it would require renaming the property. For all of these reasons, I think the approach needs closer consideration. It may warrant a different service implementation, rather than changes to the existing implementations.

[exceptionfactory]

Closing this pull request for now, glad to discuss further options on the referenced Jira issue to decide on the best path forward before returning to code review.