refactor: modern Kotlin for the Android layer + AGP 8 / SDK 35 build modernization

[tony19]

Summary

Modernizes logback-android for current Android tooling and converts the Android-specific layer to idiomatic Kotlin.

Build modernization (commit 1)

• Kotlin DSL + version catalog: build.gradle → build.gradle.kts (root, module, settings), dependencies/plugins centralized in gradle/libs.versions.toml
• AGP 7.4.2 → 8.7.3, Gradle wrapper 8.1.1 → 8.14.3, Kotlin 2.1.21 with explicit API mode
• compileSdk 31 → 35, minSdk 9 → 21, Java bytecode target 1.6 → 17 (matching AGP 8's JDK-17 baseline)
• Robolectric 4.10.3 → 4.14.1 (required for compileSdk 35); slf4j 2.0.7 → 2.0.17
• Replaced AGP options removed in AGP 8: library versionCode/targetSdkVersion (now testOptions.targetSdk + lint.targetSdk), android.disableAutomaticComponentCreation (now publishing.singleVariant("release")), org.gradle.unsafe.configuration-cache → stable name
• Added a GitHub Actions build workflow (assemble + unit tests + lint, with a failed-test summary on failure) — the repo previously had no build CI
• gradle/publish-*.gradle are intentionally left as Groovy apply(from:) scripts to keep the release pipeline untouched; gradle/analysis.gradle and gradle/docs.gradle are unreferenced/dead and were left as-is

Kotlin conversion of the Android layer (commit 2)

Converted to modern Kotlin under src/main/kotlin (properties, when, use, fun interfaces, null-safety):

• ch.qos.logback.classic.android: LogcatAppender, SQLiteAppender, BasicLogcatConfigurator, SQLiteLogCleaner, Clock, SystemClock
• ch.qos.logback.core.android: AndroidContextUtil, SystemPropertiesProxy

The upstream-derived logback core/classic port (~400 files) intentionally stays in Java so future diffs against upstream logback remain reviewable.

Java/XML-config interop preserved: property accessors compile to the original getter/setter signatures (Joran reflection unaffected), @JvmStatic/@JvmOverloads keep static entry points (BasicLogcatConfigurator.configure(), AndroidContextUtil.containsProperties(), SystemPropertiesProxy.getInstance()), @JvmName keeps the package-private setClock test hook unmangled, and SQLiteLogCleaner is a fun interface so existing Java anonymous classes still compile. Existing Java tests compile and run against the converted classes.

Recent-Android fixes while converting:

• PackageInfo.versionCode → longVersionCode on API 28+; getPackageInfo uses PackageInfoFlags on API 33+
• Removed obsolete pre-21 paths (@TargetApi(8/21), SDK_INT >= 21 guard) now that minSdk is 21
• SQLiteAppender.stop()/finalize() no longer NPE when the appender never started

CI + test modernization (commits 3–7)

• CircleCI image cimg/android:2023.02.1 → 2024.11.1 (JDK 17 for AGP 8) and cache keys updated for the Kotlin DSL files
• Mockito 2.28.2 → 5.12.0: the old subclass mockmaker corrupts mocks of JDK classes on JDK 17+, which failed ~50 socket-appender tests; migrated the two test files using removed APIs (Matchers → ArgumentMatchers, anyObject() → any(), verifyZeroInteractions → verifyNoInteractions)
• AsyncAppenderBaseTest: replaced Thread.suspend/resume (removed in JDK 20+) and adjusted for JDK 19+ retaining a terminated thread's interrupt status
• Kept the org.robolectric:android-all test dependency: besides its documented pre-21 purpose it supplies real Android classes (TextUtils used by FileFinder) to unit tests that don't run under the Robolectric runner
• AndroidContextUtilTest: Robolectric 4.14 emulates the real external-files path layout, so the test compares against the context's value instead of a hard-coded suffix
• De-flaked AbstractSocketAppenderTest (async-dispatcher verifications): verify timeout 1s → 5s plus a RetryRule (3 attempts, fresh setup/teardown per attempt; consistent failures still fail)

Verification

This sandbox cannot reach dl.google.com/maven.google.com, so AGP couldn't run here; verification was done with the same compilers CI uses, against Maven-Central artifacts: full main-source compile (kotlinc -Xexplicit-api=strict -jvm-target 17 + javac --release 17), full test-source compile, and a 920-test local JUnit+Robolectric run — plus an A/B run of the identical harness against unmodified main showing zero regressions from this PR's code.

CI status (as of aa12207)

• GitHub Actions build (assemble + testReleaseUnitTest + lint): ✅ green
• CircleCI build / lint: ✅ green
• CircleCI test: ❌ — its logs aren't reachable from this sandbox; the failing tests should be listed in the CircleCI UI (store_test_results). The identical suite passes on GitHub Actions on the same commit, so the delta is either the debug-variant run or executor-specific flakiness.
• CircleCI test_app: ❌ — builds tony19-sandbox/logback-test-app against the new AAR; that external app's toolchain likely needs AGP 7.4+/JDK 17 to consume Java-17 bytecode. Needs a maintainer look.
• Codacy: action_required — needs a maintainer to review in the Codacy UI.

🤖 Generated with Claude Code

https://claude.ai/code/session_01UCK17vyzha2TXKfm6UJCom

[tony19]

Status: GitHub Actions is fully green (assemble + all 993 release-variant unit tests + lint) as of aa12207, after fixing Mockito-on-JDK-17 mocking, the android-all test classpath, two JDK-20+ test incompatibilities, and de-flaking the async socket-appender suite.

CircleCI test and test_app are still red, and I can't see their logs from this environment (only the CircleCI UI has them, via store_test_results). Two asks when you get a chance, @tony19:

1. Could you paste the failing test names from the CircleCI test job? The identical suite passes on GitHub Actions on the same commit, so I suspect either a debug-variant-only issue or executor flakiness — with the list I can fix it directly.
2. test_app builds tony19-sandbox/logback-test-app against the new AAR. This PR moves the library to Java 17 bytecode (AGP 8 baseline), so that app likely needs AGP 7.4+/JDK 17 to consume it — its toolchain is outside this repo, so it needs a change there (happy to advise on the specifics).

🤖 Generated with Claude Code

---

Generated by Claude Code