perf: contrib.bom.utils.BomDependencyGraphFlatMerger._flatten_merge

[jkowalleck]

caused by #997 (comment)

[Copilot]

Pull request overview

This PR improves the runtime performance of cyclonedx.contrib.bom.utils.BomDependencyGraphFlatMerger._flatten_merge by optimizing how already-visited Dependency objects are tracked during graph traversal, addressing feedback from the earlier introduction of this utility (#997).

Changes:

• Replace the seen container from list[int] to set[int] to make id(todo) in seen checks O(1) instead of O(n).
• Update the corresponding mutation from append() to add().

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[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 0 complexity · 0 duplication

Metric	Results
Complexity	0
Duplication	0

View in Codacy

🟢 Coverage 100.00% diff coverage · +0.00% coverage variation

Metric	Results
Coverage variation	✅ +0.00% coverage variation
Diff coverage	✅ 100.00% diff coverage (80.00%)

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (78b8d8b)	6078	5728	94.24%
Head commit (372a36a)	6078 (+0)	5728 (+0)	94.24% (+0.00%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#999)	2	2	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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