[manoelcampos]

Closes #587. Builds on the Listeners helper from #586.

Changes

Part of #587	What changed	Saved per Cloudlet
1. Listener sets	The 3 HashSets are now immutable lists that start as the shared List.of() and change through Listeners. Notifications use for-each loops.	~192 B
2. requiredFiles	Starts as List.of(); a real ArrayList is only created on the first addRequiredFile. deleteRequiredFile is now a single remove(filename) (was O(n²) on a LinkedList). setRequiredFiles copies the given list, so an immutable list no longer breaks later adds.	~32 B
3. Shared FULL model	New immutable UtilizationModel.FULL (backed by UtilizationModelFullShared, whose setters do nothing), used as the default CPU model.	~24 B

Total: ~248 B per Cloudlet (~248 MB per 1M Cloudlets).

Behavior changes

• getRequiredFiles() returns a read-only list (use addRequiredFile/deleteRequiredFile).
• The onFinish listener list is cleared before notifying, so a listener added during the finish notification is kept for a later finish (consistent with Listener lists: lazy creation and safe changes during notification #586). Before, it was dropped.
• Listeners.remove(list, null) returns the same list instead of throwing an NPE (List.of().indexOf(null) throws). This kept removeOnFinishListener(null) returning false, as before.
• Setters on UtilizationModel.FULL do nothing. Users who need a configurable model can create new UtilizationModelFull().

Tests

• mvn clean verify -Pintegration-tests: 583 tests, all passing.
• New tests: shared UtilizationModel.FULL and its no-op setters; listener duplicates, self-removal and addition during notification; requiredFiles cases (immutable list given to the setter, delete with no files, add after deleting all files, read-only getter); Listeners.remove with null.
• Examples CloudletListenersExample1, CreateCloudletAfterLastFinishedOne and DynamicCreationOfVmsAndCloudletsExample ran with no exceptions, with the same output as on master.

Benchmark results

Measured with MemoryFootprintBenchmark (cloudsimplus/cloudsimplus-benchmarks#10). It creates 100,000 Cloudlets and measures the heap they keep after a full GC (median of 5 rounds).

Class	Before	After	Saved per object
CloudletSimple	464 B	216 B	248 B (−53.4%)

The measured saving matches the estimate in the table above, which splits it among the 3 changes. That's about 248 MB less heap per 1M Cloudlets.

"Before" is CloudSim Plus 8.5.1, so the difference includes all changes since that version, but it's exactly the saving estimated for this PR. Run with JDK 25.0.4 (Corretto), compressed oops, -XX:+UseSerialGC.

🤖 Generated with Claude Code

[codacy-production]

Up to standards ✅

🟢 Issues 0 issues

Results:
0 new issues

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🟢 Metrics 21 complexity · 0 duplication

Metric	Results
Complexity	21
Duplication	0

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🟢 Coverage 83.67% diff coverage · +0.16% coverage variation

Metric	Results
Coverage variation	✅ +0.16% coverage variation
Diff coverage	✅ 83.67% diff coverage

View coverage diff in Codacy

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (0813444)	9111	4630	50.82%
Head commit (06b0eab)	9136 (+25)	4657 (+27)	50.97% (+0.16%)

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 (#594)	49	41	83.67%

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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