turn getRetiringFederationCreationTime to return an optional

[julianlen]

Description

Motivation and Context

How Has This Been Tested?

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• Tests for the changes have been added (for bug fixes / features)
• Requires Activation Code (Hard Fork)

• Other information:

[github-actions]

Dependency Review

✅ No vulnerabilities or license issues or OpenSSF Scorecard issues found.

Scanned Files

None

[Copilot]

Pull request overview

This PR refactors the getRetiringFederationCreationTime method to return an Optional<Instant> instead of a nullable Instant, improving null safety and making the API more explicit about the possibility of no retiring federation existing.

Key Changes:

• Changed return type from Instant to Optional<Instant> for getRetiringFederationCreationTime across the interface and implementation layers
• Updated test cases to verify Optional.isEmpty() instead of null checks
• Refactored the Bridge class to use functional programming patterns with Optional.map() and Optional.orElse()

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
rskj-core/src/main/java/co/rsk/peg/federation/FederationSupport.java	Updated interface method signature to return Optional<Instant>
rskj-core/src/main/java/co/rsk/peg/federation/FederationSupportImpl.java	Changed implementation to return Optional directly instead of .orElse(null)
rskj-core/src/main/java/co/rsk/peg/BridgeSupport.java	Updated method signature to match interface change
rskj-core/src/main/java/co/rsk/peg/Bridge.java	Refactored to use Optional and extracted epoch time logic into a private method
rskj-core/src/test/java/co/rsk/peg/federation/FederationSupportImplTest.java	Updated test assertions to check isEmpty() instead of null values
rskj-core/src/test/java/co/rsk/peg/BridgeSupportTest.java	Updated mock returns and assertions to use Optional
rskj-core/src/test/java/co/rsk/peg/BridgeTest.java	Updated mock to return Optional value
rskj-core/src/test/java/co/rsk/peg/BridgeSupportIT.java	Updated integration test to unwrap Optional before assertions

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[jeremy-then]

LGTM.

[marcos-iov]

Suggested change

	private Long getEpochTimeBasedOnActivation(Instant retiringFederationCreationTime) {
	private Long getFederationCreationTiimeEpochBasedOnActivation(Instant federationCreationTime) {

Make it clear that it applies to federation creation time, not to any epoch. Can/should this be re-used when getting active federation creation time?

[julia-zack]

marcos is right, this same logic is being applied for getFederationCreationTime

[julianlen]

done!

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud