Retire Maven Wrapper, add contributor docs, and introduce code-review quality gates

[peter-lawrey]

This PR removes the obsolete Takari Maven Wrapper downloader, introduces a reusable code-review Maven profile (Checkstyle, SpotBugs+FindSecBugs, PMD, JaCoCo), refreshes and expands project documentation, aligns copyrights/branding with chronicle.software (2014-2025), and adds targeted tests and minor refactors to tighten behaviour and style.

Why

• The Takari downloader (.mvn/wrapper/MavenWrapperDownloader.java + maven-wrapper.properties) is legacy and unnecessary in CI and developer environments that already provision Maven.
• We want a repeatable, automated code-review gate to standardise static analysis across Chronicle repos.
• Documentation drift made it harder for agents and new contributors to work cleanly; we add authoritative, linkable AsciiDoc.
• Legal/branding headers needed updating.

What changed

Build & repo hygiene

• 🔥 Remove Takari wrapper downloader
  Deletes .mvn/wrapper/MavenWrapperDownloader.java and .mvn/wrapper/maven-wrapper.properties.

• 🛠 Add code-review Maven profile (opt-in):

  • Checkstyle (src/main/config/checkstyle.xml)
  • SpotBugs + FindSecBugs (src/main/config/spotbugs-exclude.xml)
  • PMD (src/main/config/pmd-ruleset.xml, pmd-exclude.properties)
  • JaCoCo with bundle thresholds (${jacoco.line.coverage}=0.918, ${jacoco.branch.coverage}=0.854)

• 📦 Pin plugin versions via properties; lift hard enforcer rules (removed maven-enforcer-plugin) to reduce friction for consumers.

• 📄 LICENSE.adoc added (Apache 2.0 pointer).

Documentation (AsciiDoc, British English, ISO-8859-1 policy)

• New AGENTS.md (house rules for humans/LLMs): language, character-set, commit/PR etiquette, doc-first loop, Nine-Box tags.

• README.adoc updates:

  • JDK matrix clarified (8, 11, 17, 21), British English, link fixes.
  • Dependency coordinates bumped in examples to 0.27ea1.
  • Adds “Internal documentation” section linking to AsciiDoc set below.

• New internal docs under src/main/docs/:

  • specifications.adoc (FN/NF/TEST/DOC/OPS)
  • architecture-overview.adoc
  • algorithm-profiles.adoc
  • invariants-and-contracts.adoc
  • testing-strategy.adoc
  • performance-benchmarks.adoc (notes TODOs)
  • unsafe-and-platform-notes.adoc
  • change-log-template.adoc

Source headers & styling

• Update headers across net.openhft.hashing.* to Copyright 2014-2025 chronicle.software.

• Micro-refactors for clarity/consistency (no behaviour change intended):

  • MetroHash: simplified rotations (removed redundant parentheses).
  • ModernCompactStringHash: idiomatic comparison.
  • MurmurHash_3/WyHash: explicit casts to long normalised.
  • Util: explicit fallback comment.

Note: LongHashFunction / LongTupleHashFunction internal helpers now reference INSTANCE directly where previously UnsafeAccess.INSTANCE was used. Tests pass; keep an eye on symbol scoping in future refactors.

Tests

• New: ByteBufferAccessTest, DualHashFunctionTest, ModernCompactStringHashTest.
• Expanded: LongHashFunctionTest (boolean slices, direct/read-only buffers, char slices).
• All tests run under mvn -q verify; tuple/long projections cross-checked.

Impact

• Developers/CI: Use your installed Maven; wrapper downloader is gone. The wrapper scripts (if any) aren’t relied upon by CI.
• Quality gate (opt-in): -Pcode-review enforces style, bug-finders, PMD, and coverage thresholds.
• Docs: Far richer internal docs for onboarding and for AI-assisted workflows.
• Runtime: No intentional behavioural changes; hashing outputs remain stable. Minor internal cleanups only.

Verification

# Standard build
mvn -q verify

# Run the code-review gate locally
mvn -q -Pcode-review verify

[sonarqubecloud]

Quality Gate passed

Issues
7 New issues
0 Accepted issues

Measures
0 Security Hotspots
92.9% Coverage on New Code
0.5% Duplication on New Code

See analysis details on SonarQube Cloud