Register generated Kotlin sources via the Kotlin Gradle plugin API

[alexander-yevsyukov]

What

Implements #185. GenerateProtoTask.configureSourceSetDirs() now registers the
copied, generated Kotlin sources through the Kotlin Gradle plugin's dedicated
KotlinSourceSet.generatedKotlin source directory set, instead of the plain
kotlin source set. The protoc output directories are still excluded from the
plain kotlin set, exactly as before.

Why

generatedKotlin (an @ExperimentalKotlinGradlePluginApi member, available in
KGP 2.3.21 which this repo uses) is the modern way to register generated Kotlin
sources. They are still compiled — allKotlinSources = kotlin + generatedKotlin,
which the Kotlin compile task consumes — but build tooling and IDEs can tell them
apart from hand-written code. This repo already reads generatedKotlin separately
in its Kover coverage configuration.

How

• GeneratedSourcePlugin.kt: resolve the matching KotlinSourceSet (via the
  non-deprecated KotlinBaseExtension) and register the copied directory under its
  generatedKotlin. A single source-set lookup drives both the exclusion and the
  registration — the Gradle source set's kotlin extension is the same object as
  KotlinSourceSet.kotlin — gated on that extension's presence to preserve the
  original timing relative to the Protobuf plugin.

Tests

No existing spec applied the Kotlin plugin, so the Kotlin path was uncovered. Added
a TestKit spec in GeneratedSourcePluginSpec that applies the Kotlin JVM +
Protobuf + this plugin and asserts that generated/main/kotlin is registered under
generatedKotlin, is absent from the plain kotlin set, and that the .kt is
copied. Because this plugin references the KGP API as compileOnly, the spec puts
the Kotlin Gradle plugin on the plugin-under-test classpath so the plugin and KGP
share a classloader (otherwise TestKit isolates them and KotlinBaseExtension
fails to resolve at runtime).

Versioning

Bumps 2.0.0-SNAPSHOT.402 → .403. The change is @Internal and non-breaking, so
a single snapshot increment.

Notes for reviewers

• Reviewed locally by the kotlin-engineer and spine-code-review agents; both
  approved, and their feedback (single source-set lookup; import the task type) is
  folded in.
• The branch also carries unrelated maintenance commits made directly on it
  (CI/config sync, IDEA settings, a dependency-report refresh).

🤖 Generated with Claude Code

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[codecov]

Codecov Report

❌ Patch coverage is 44.44444% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.73%. Comparing base (bd9ea3a) to head (1a3bbd4).

Additional details and impacted files

@@             Coverage Diff              @@
##             master     #186      +/-   ##
============================================
+ Coverage     90.45%   90.73%   +0.27%     
  Complexity      554      554              
============================================
  Files           122      122              
  Lines          2243     2246       +3     
  Branches        311      313       +2     
============================================
+ Hits           2029     2038       +9     
+ Misses           93       86       -7     
- Partials        121      122       +1     

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[Copilot]

Pull request overview

This PR implements issue #185 by updating the Protobuf generated-sources wiring for Kotlin so that copied generated Kotlin sources are registered via the Kotlin Gradle plugin’s dedicated KotlinSourceSet.generatedKotlin directory set (while still excluding protoc output directories from the plain kotlin set). It also includes several additional build/publishing guard and dependency-maintenance updates carried on the same branch.

Changes:

• Register copied generated Kotlin sources under generatedKotlin (instead of kotlin) and add a Gradle TestKit spec covering Kotlin + Protobuf + this plugin.
• Extend version-guard/publishing infrastructure in buildSrc (base-branch comparison, Maven metadata parsing, version comparator, and task wiring).
• Update snapshot versions and regenerate dependency reports / dependency constants.

Reviewed changes

Copilot reviewed 42 out of 43 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
version.gradle.kts	Bumps publishing snapshot version to 2.0.0-SNAPSHOT.403.
protobuf-setup-plugins/src/test/kotlin/io/spine/tools/protobuf/gradle/plugin/GeneratedSourcePluginSpec.kt	Adds TestKit coverage asserting generatedKotlin registration and exclusion from plain kotlin.
protobuf-setup-plugins/src/main/kotlin/io/spine/tools/protobuf/gradle/plugin/GeneratedSourcePlugin.kt	Switches Kotlin generated dir registration to KotlinSourceSet.generatedKotlin and adds Kotlin source set lookup.
protobuf-setup-plugins/build.gradle.kts	Adds Kotlin Gradle plugin to plugin-under-test classpath for TestKit isolation.
docs/dependencies/pom.xml	Updates documented versions to the new snapshot and refreshed dependency versions.
docs/dependencies/dependencies.md	Regenerates dependency report for the new snapshot (includes updated generation timestamp).
buildSrc/src/test/kotlin/io/spine/gradle/VersionGradleFileSpec.kt	Adds unit tests for parsing version.gradle.kts publishing version declarations.
buildSrc/src/test/kotlin/io/spine/gradle/VersionComparatorSpec.kt	Adds tests for semantic-ish version comparison logic.
buildSrc/src/test/kotlin/io/spine/gradle/publish/MavenMetadataSpec.kt	Adds a Jackson XML round-trip test ensuring Maven metadata deserialization preserves versions.
buildSrc/src/test/kotlin/io/spine/gradle/publish/IncrementGuardTest.kt	Expands IncrementGuard tests (CI/local publish scenarios, task wiring).
buildSrc/src/main/kotlin/kmp-module.gradle.kts	Skips forced-resolution logic for Dokka configurations.
buildSrc/src/main/kotlin/jvm-module.gradle.kts	Skips forced-resolution logic for Dokka configurations.
buildSrc/src/main/kotlin/io/spine/gradle/VersionGradleFile.kt	Introduces parser/reader for version.gradle.kts, including base-branch reading via git show.
buildSrc/src/main/kotlin/io/spine/gradle/VersionComparator.kt	Introduces comparator for “newest version” selection and base-branch increment checks.
buildSrc/src/main/kotlin/io/spine/gradle/report/pom/DependencyWriter.kt	Uses VersionComparator to pick newest duplicate dependency versions deterministically.
buildSrc/src/main/kotlin/io/spine/gradle/publish/MavenMetadata.kt	Extracts Maven metadata XML model + fetch/parse helper.
buildSrc/src/main/kotlin/io/spine/gradle/publish/IncrementGuard.kt	Reworks checkVersionIncrement execution conditions and wires it before publishToMavenLocal.
buildSrc/src/main/kotlin/io/spine/gradle/publish/CheckVersionIncrement.kt	Adds base-branch increment comparison and reuses extracted Maven metadata + version parsing/comparison.
buildSrc/src/main/kotlin/io/spine/gradle/kotlin/KotlinConfig.kt	Refactors compiler opt-ins; scopes ExperimentalPathApi opt-in to JVM compilations only.
buildSrc/src/main/kotlin/io/spine/dependency/test/Testcontainers.kt	Improves documentation and clarifies provided Testcontainers modules.
buildSrc/src/main/kotlin/io/spine/dependency/storage/QueryDsl.kt	Adds QueryDSL dependency definition.
buildSrc/src/main/kotlin/io/spine/dependency/storage/PostgreSql.kt	Adds PostgreSQL JDBC driver dependency definition.
buildSrc/src/main/kotlin/io/spine/dependency/storage/MySql.kt	Adds MySQL Connector/J dependency definition.
buildSrc/src/main/kotlin/io/spine/dependency/storage/HsqlDb.kt	Adds HSQLDB dependency definition.
buildSrc/src/main/kotlin/io/spine/dependency/storage/Hikari.kt	Adds HikariCP dependency definition.
buildSrc/src/main/kotlin/io/spine/dependency/storage/H2.kt	Adds H2 dependency definition.
buildSrc/src/main/kotlin/io/spine/dependency/local/ToolBase.kt	Updates ToolBase dependency snapshot version constants.
buildSrc/src/main/kotlin/io/spine/dependency/local/Logging.kt	Updates Spine Logging snapshot version constant.
buildSrc/src/main/kotlin/io/spine/dependency/local/CoreJvmCompiler.kt	Updates Core JVM Compiler snapshot version constants.
buildSrc/src/main/kotlin/io/spine/dependency/local/CoreJvm.kt	Updates Spine Core JVM snapshot version constant.
buildSrc/src/main/kotlin/io/spine/dependency/local/Compiler.kt	Updates fallback compiler snapshot versions.
buildSrc/src/main/kotlin/io/spine/dependency/local/Base.kt	Updates Spine Base snapshot version constants.
buildSrc/src/main/kotlin/io/spine/dependency/Dependency.kt	Adds Configuration.isDokka helper to avoid forcing versions on Dokka configs.
buildSrc/src/main/kotlin/io/spine/dependency/boms/BomsPlugin.kt	Excludes Dokka configurations from BOM-related forcing logic.
buildSrc/src/main/kotlin/dokka-setup.gradle.kts	Disables Dokka Javadoc publication task for KMP modules.
buildSrc/src/main/kotlin/DependencyResolution.kt	Skips forced-resolution logic for Dokka configurations.
.idea/kotlinc.xml	Config-managed/IDE settings update (not reviewed).
.github/workflows/revalidate-versions.yml	Config-managed workflow addition (not reviewed).
.github/workflows/publish.yml	Config-managed workflow update (not reviewed).
.github/workflows/increment-guard.yml	Config-managed workflow update (not reviewed).
.github/workflows/build-on-ubuntu.yml	Config-managed workflow update (not reviewed).
.claude/settings.json	Config-managed tool settings update (not reviewed).

Files not reviewed (1)

• .idea/kotlinc.xml: Generated file