Fix 25 latent test failures surfaced by enabling JUnit Platform on KMP jvmTest

[alexander-yevsyukov]

What changed

The kmp-module convention never enabled the JUnit Platform on the KMP jvmTest task, so :logging:jvmTest has been silently discovering zero tests while behavior drifted from the Flogger contract during the Java-to-Kotlin migration. This PR enables the platform in the convention (mirroring module-testing, without an engine filter since kmp-module adds the Kotest runner — a JUnit Platform engine of its own), removes the now-superseded module-local workaround in otel-backend, and fixes the 25 latent failures this surfaced: :logging:jvmTest now runs 232/232 green.

Production fixes (Flogger-contract drift)

• MetadataKey.cast() throws ClassCastException on a type mismatch again instead of silently returning null (the message reports the value class, never invoking a user toString()).
• checkCannotRepeat() throws IllegalArgumentException per the documented contract of findValue()/getSingleValue(); its message was also inverted.
• MetadataHandler.Builder.addRepeatedHandler() required a key that cannot repeat — the exact opposite of Flogger's checkArgument(key.canRepeat()).
• SimpleProcessor lost Collections.unmodifiableList in translation (e.setValue(e.value as List<*>) was a no-op cast); repeated values now dispatch through an iterator whose remove() throws.
• LogContext evaluated the lazy message lambda before AbstractLogger.write(), outside the recursion guard and robust error handling — a throwing toString() propagated to callers and reentrant logging hit StackOverflowError. Evaluation now happens inside write(data, prepare) (@JvmOverloads preserves the old JVM signature). A null message also reaches the backend as null instead of the string "null".
• AbstractLogger.atConfig() mapped to Level.INFO (copy-paste); now Level.CONFIG.
• Logging-error timestamps now include milliseconds and the UTC offset (yyyy-MM-dd'T'HH:mm:ss.SSSZ equivalent).
• LogPerBucketingStrategy.byClass()/byClassName() used key::class/qualifiedName!! — no identity guarantee and an NPE for local/anonymous classes; now key.javaClass/.name.
• ScopedLoggingContext.Builder.run(Runnable) was missing, so .run { } silently bound to Kotlin's stdlib run and never installed the context; the member is restored.

Test fixes (stale or Java-specific expectations)

Invocation counters moved out of lazy log lambdas (they only run for statements that actually log), the * spread operator for vararg arrays, Kotlin qualified names in LogLevelMapSpec, and message-format alignments. Full per-failure triage rationale: .agents/tasks/logging-jvmtest-triage.md.

Reviewer notes

• Must-not-forget follow-up: buildSrc/src/main/kotlin/kmp-module.gradle.kts is config-distributed — the same jvmTest wiring must land in SpineEventEngine/config, or the next ./config/pull reverts it and jvmTest silently drops back to zero tests (a follow-up task is queued for this).
• The version bump also restores the canonical val versionToPublish: String by extra("…") shape; the previous bump commit introduced extra.set(…), which the version-bumped guard script cannot parse.
• One deliberate non-fix: AbstractLogger.write() catches RuntimeException around the message evaluation, which would also contain a CancellationException raised from user code reachable via toString(). This matches Flogger's "log statements never throw" contract and the lambdas are non-suspending, so it is left as-is — flagging for awareness.
• Copyright headers of Flogger-ported files keep the The Flogger Authors; attribution (also restored in MetadataKey.kt, where it had been lost on master).

Pre-PR checklist: ./gradlew build dokkaGenerate green (all modules, detekt, Kover); reviewers kotlin-engineer, spine-code-review, review-docs all APPROVE WITH CHANGES, applied or tracked as above.

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR restores effective JVM test execution for the logging KMP module by enabling JUnit Platform for jvmTest, then fixes the production/test regressions that were previously masked by “0 tests discovered”. It also realigns several logging behaviors with the Flogger contract and updates documentation/version artifacts accordingly.

Changes:

• Enable JUnit Platform on KMP jvmTest (and remove the module-local otel-backend workaround).
• Fix Flogger-contract drift in core logging (lazy message evaluation inside write(), correct atConfig() level, repeated-metadata immutability, stricter MetadataKey.cast(), safer bucketing strategy keys, restored ScopedLoggingContext.Builder.run(Runnable)).
• Update tests and generated docs/version references to match the corrected behavior.

Reviewed changes

Copilot reviewed 19 out of 19 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
version.gradle.kts	Bumps versionToPublish to 2.0.0-SNAPSHOT.422 using the delegated extra property shape.
logging/src/jvmTest/kotlin/io/spine/logging/test/LoggingCompatibilityTest.kt	Fixes Kotlin vararg array passing via spread operator in compatibility test.
logging/src/jvmTest/kotlin/io/spine/logging/LogContextSpec.kt	Updates expectations for null literal message handling and formatting behavior.
logging/src/jvmTest/kotlin/io/spine/logging/JvmLoggerSpec.kt	Aligns log-site/method-name expectation and moves counters outside lazy message lambdas.
logging/src/jvmTest/kotlin/io/spine/logging/backend/AnyExtsJvmSpec.kt	Updates expectation to match backtick diagnostic style for toString() returning null.
logging/src/commonTest/kotlin/io/spine/logging/context/LogLevelMapSpec.kt	Adjusts mapped logger-name expectations to Kotlin qualified names (e.g., kotlin.String).
logging/src/commonTest/kotlin/io/spine/logging/AbstractLoggerSpec.kt	Makes recursion error assertion case-insensitive.
logging/src/commonMain/kotlin/io/spine/logging/MetadataKey.kt	Restores Flogger-like cast() behavior (throw on mismatch) and corrects checkCannotRepeat() exception type/message.
logging/src/commonMain/kotlin/io/spine/logging/LogPerBucketingStrategy.kt	Uses JVM class identity/name for bucketing to avoid KClass identity/NPE issues.
logging/src/commonMain/kotlin/io/spine/logging/LogContext.kt	Defers lazy message evaluation into AbstractLogger.write() recursion guard and preserves null literal behavior to backend.
logging/src/commonMain/kotlin/io/spine/logging/context/ScopedLoggingContext.kt	Restores Builder.run(Runnable) to avoid stdlib run shadowing and ensure context installation.
logging/src/commonMain/kotlin/io/spine/logging/backend/MetadataProcessor.kt	Ensures repeated metadata iteration is non-modifiable via an iterator wrapper that throws on remove().
logging/src/commonMain/kotlin/io/spine/logging/backend/MetadataHandler.kt	Fixes repeated-handler registration to require key.canRepeat() (and documents the thrown IllegalArgumentException).
logging/src/commonMain/kotlin/io/spine/logging/AbstractLogger.kt	Fixes atConfig() level, moves message evaluation into write(data, prepare), and improves logging-error timestamp formatting (millis + UTC offset).
docs/dependencies/pom.xml	Updates docs dependency POM version to 2.0.0-SNAPSHOT.422.
docs/dependencies/dependencies.md	Updates generated dependency report version headers/timestamps to match the bumped snapshot.
buildSrc/src/main/kotlin/kmp-module.gradle.kts	Configures KMP jvmTest to use JUnit Platform and test logging (config-distributed file).
backends/otel-backend/build.gradle.kts	Removes now-superseded local jvmTest JUnit Platform/test logging workaround.
.agents/tasks/logging-jvmtest-triage.md	Adds a triage note capturing failure analysis and rationale (config-managed path).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 67.87%. Comparing base (cf43e4b) to head (13222bd).

Additional details and impacted files

@@                       Coverage Diff                       @@
##             claude/angry-hugle-d62cfe     #147      +/-   ##
===============================================================
+ Coverage                        67.80%   67.87%   +0.06%     
  Complexity                         464      464              
===============================================================
  Files                              109      109              
  Lines                             2578     2574       -4     
  Branches                           403      402       -1     
===============================================================
- Hits                              1748     1747       -1     
+ Misses                             696      694       -2     
+ Partials                           134      133       -1     

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[alexander-yevsyukov]

Closing as incorrect. We want to use fully qualified Kotlin class names in LogLevelMap, not Java class names.