NIFI-16283 Support changing Connector versions

[markap14]

https://issues.apache.org/jira/browse/NIFI-16283

Summary

• support changing Connector bundle versions through the REST API, web UI, and toolkit CLI
• migrate Connector configuration and managed flow state while replacing the implementation
• create a GhostConnector when the target implementation cannot be instantiated
• add audit records, available-version metadata, and end-to-end system-test coverage

Testing

• framework Connector node and reload unit tests
• web API facade, DAO, DTO, and audit unit tests
• toolkit CLI unit tests
• Connector frontend and shared utility unit tests and lint
• ConnectorChangeVersionIT
• Checkstyle and PMD for affected Java modules

All listed tests passed before rebasing onto the main branch version change to 2.13.0-SNAPSHOT. A post-rebase local Maven run could not begin compilation because the local Maven repository does not yet contain the new 2.13.0-SNAPSHOT reactor artifacts; CI will build those artifacts from the full reactor.

[mcgilman]

Reviewed with emphasis on the connector version-change UI and its supporting framework behavior.

[bobpaulin]

@markap14 Thanks for this change! Had one request on test coverage. Will do some testing on this and report back and findings.

[markap14]

[grok-4.6] I have moved this PR to draft. My last commit (d3035f2) was a mistake and should not be merged.

In response to @bobpaulin's request for revert coverage, I changed StandardConnectorNode so that any stored property or configuration step the current Connector version does not declare is silently dropped after migrateProperties. That is wrong. Deleting a user's configured values is destructive and is not a decision the framework should make on its own, and it was well outside the test coverage that was actually asked for.

I am reverting that behavior and working out the correct approach for what should happen when a version change leaves behind values the target version does not declare. I will update this PR when that is settled.

[markap14]

[grok-4.6] Correction pushed as b4b8ca8. The PR is still in draft until the full system test suite finishes.

To be clear about what changed versus my earlier mistake: the framework still discards a stored property or configuration step that the current Connector version does not declare, but it no longer treats that as a free-standing deletion. Two things it deliberately does not do at that moment:

• it does not push the configuration to the ConnectorConfigurationProvider
• it does not reclaim any Asset the discarded value referenced

Those happen when the user applies a configuration, which is the point at which the configuration is pushed to the provider and Assets no longer referenced by either the active or working configuration are reclaimed. An Asset stays available until then.

Why discard at all: the stored value is not visible to the current version, and StandardConnectorConfigurationContext.setProperties merges rather than replaces, so the UI cannot clear a property it does not know exists. Left in place, the Connector reports invalid for a property the user has no way to remove.

Tests:

• TestStandardConnectorNode verifies a replacement drops an undeclared property and configuration step, keeps declared values, and leaves the referenced Asset intact. Verified it fails without the change.
• TestStandardConnectorRepository verifies applying an update reclaims Assets no longer referenced. Verified it fails if the cleanup call is removed.
• ConnectorChangeVersionIT now changes 1.0.0 to 2.0.0 and back, then exercises Troubleshooting on the reverted version.

All 57 connector system tests and the 760 nifi-framework-core unit tests pass.