NIFI-16058 - Treat external controller service reference changes in versioned flows as environment-specific

[pvillard31]

Summary

NIFI-16058 - Treat external controller service reference changes in versioned flows as environment-specific

NIFI-15697 (PR #11006) fixed a badge/dialog inconsistency for external controller service references via three changes: (1) removed the comparator suppression of external CS reference diffs, (2) added name-based reconciliation of the snapshot, (3) added cache invalidation when an ancestor CS is removed. (3) was the real fix; (1)+(2) changed prior behavior and caused NIFI-16058: external CS references (e.g. a root SSL Context Service) now show as phantom local changes when the service differs by id, and name-based reconciliation can't help when the name differs across envs.

This keeps (3) and restores environment-specific treatment of external CS references, but in the flow-difference filter (FlowDifferenceFilters.isEnvironmentalChange) rather than the framework-agnostic comparator: a CS-reference change is environmental when the snapshot value isn't a locally-accessible ancestor service while the local value is. The filter runs on both the state and "Show Local Changes" paths, so they agree by construction. Name-based reconciliation is removed; StandardFlowComparator is unchanged.

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