Initialize trusted block providers only once

[majesticsky]

Fixes #7973 — the review comment it points to:
#7966 (comment)

getTrustedBsqBlockProviders() used the emptiness of the provider set as its lazy initialization guard. An empty set is a legitimate outcome: regtest bundles no providers, the resource file can be absent, and the deny list may filter out every entry. In those cases, lazyInitialize() ran again on every call, re-reading the resource on a path that DaoBlockSignatureVerifier walks per block.

Populating the set in place also handed callers a live reference to it, and left it briefly empty between clear() and addAll(). Every caller reaches this singleton on the user thread today, so that window is not observable in practice, but nothing in the class enforces it.

Track initialization in an explicit flag, synchronize the accessor, and publish the providers as an immutable set, so the guard is atomic and callers cannot mutate shared state.

Two new tests cover this; both fail without the production change.

Summary by CodeRabbit

• Bug Fixes
  • Improved trusted block provider loading so initialization occurs reliably and only once, including when no providers are available.
  • Prevented accidental modification of the trusted provider list after it has been loaded.
  • Improved consistency when accessing trusted block provider information from multiple operations.

[boring-cyborg]

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Team

Run ID: 849622b4-ca71-42ad-a81a-cb1460c42c20

📥 Commits

Reviewing files that changed from the base of the PR and between 3875ed4 and dcf9916.

📒 Files selected for processing (2)

• core/src/main/java/bisq/core/dao/node/block_provider/TrustedBsqBlockProviderRepository.java
• core/src/test/java/bisq/core/dao/node/block_provider/TrustedBsqBlockProviderRepositoryTest.java

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📝 Walkthrough

Walkthrough

TrustedBsqBlockProviderRepository now uses an explicit initialization flag, synchronized lazy initialization, and immutable provider storage. Tests verify one-time initialization when no providers load and reject collection mutation.

Changes

Trusted BSQ provider initialization

Layer / File(s)	Summary
Explicit initialization and immutable storage core/src/main/java/bisq/core/dao/node/block_provider/TrustedBsqBlockProviderRepository.java	The repository tracks initialization with a boolean flag, synchronizes provider access, and stores loaded providers with Set.copyOf(...).
Initialization behavior tests core/src/test/java/bisq/core/dao/node/block_provider/TrustedBsqBlockProviderRepositoryTest.java	Tests verify that empty initialization runs once and that the returned provider collection is unmodifiable.

Estimated code review effort: 2 (Simple) | ~10 minutes

Merge Risk: ⚪ Minimal · up to dcf99

Trusted provider initialization now runs once even when no providers are available, and callers receive an immutable provider collection. The covered behavior has no remaining actionable merge risk.

Suggested reviewers: henrikjannsen

Poem

A rabbit checks the provider set,
Then marks the setup done.
Immutable leaves stay in their place,
No second load can run.
The tests hop twice and find it true,
While clear commands are shunned.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	The changes satisfy issue [#7973] by adding an explicit initialized flag and using it to prevent repeated initialization. The tests cover empty-provider initialization and immutable provider access.
Out of Scope Changes check	✅ Passed	The synchronization, immutable set handling, and focused tests support the initialization fix and the stated pull request objectives. No unrelated changes are present.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: ensuring that trusted block providers initialize only once.

• Fix all pre-merge checks with AI

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[majesticsky]

CI is green on my fork for this commit — ubuntu-24.04, macos-15 and
windows-2025 on Java 21.0.6:
https://github.com/majesticsky/bisq/actions/runs/33975169843