test: add Java and Kotlin consumer fixtures built against the published artifacts

[nickolas-dimitrakas]

Summary

Adds two small, unpublished com.android.library modules under compat/ that compile against the published com.mparticle:android-core (R8-minified) and com.mparticle:android-kit-base artifacts the way an integrating app and a third-party kit do: java-consumer from Java and kotlin-consumer from Kotlin with allWarningsAsErrors. Each exercises the documented API and a KitIntegration subclass that implements every listener interface. Nothing runs; the modules exist to fail to compile when the shipped API changes in a way the module build cannot see.

• settings-compat.gradle keeps the modules out of the main build, like the kits.
• Both modules resolve com.mparticle only from mavenLocal() at the version under review, mirroring KitPlugin.configureRepositories, so the previous Maven Central release can never be picked up by mistake.
• CI: one new step in the Kit Compatibility Test job runs ./gradlew -c settings-compat.gradle assembleDebug after the kit release tests, where core has already been published to Maven Local.
• compat/README.md explains the purpose and how to run the fixtures locally.

Finding

Compiling the Kotlin fixture against the published 6.1.2 AAR fails on CoreCallbacks.KitListener.Companion and .EMPTY with Unresolved reference 'Companion'. R8 renames the companion object to KitListener$b while the retained kotlin.Metadata still names Companion, so Kotlin consumers cannot resolve it (Java consumers can, since EMPTY survives as a static field on the interface). The probe was removed from the fixture so the module builds; the fix is a ProGuard-rules change and will come as its own pull request.

Verification

• ./gradlew publishMavenPublicationToMavenLocal -PVERSION=6.1.2, then ./gradlew -c settings-compat.gradle assembleDebug -PVERSION=6.1.2: passes with no warnings.
• ./gradlew -c settings-compat.gradle ktlintCheck: passes.
• Negative test pinned to 6.1.1 (on Maven Central, not in ~/.m2) fails resolution, confirming Central is excluded for com.mparticle.

Follow-ups

• Add ./gradlew -c settings-compat.gradle ktlintCheck to the Kotlin Lint Checks job so fixture formatting is enforced in CI.
• Derive the fixtures' JVM target from JAVA_VERSION in gradle.properties rather than a literal.

🤖 Generated with Claude Code

[github-actions]

📦 SDK Size Impact Report

What the SDK adds to a minified release APK.

Measured against an empty baseline app. Unlike the Rokt kit, android-core ships no Compose and no resources, so there is nothing here that a host app would already provide.

mParticle Core SDK

Metric	Target branch	This PR	Change
APK size	119.79 KB	119.78 KB	-6 bytes
Download size	117.60 KB	117.60 KB	-2 bytes
Dex bytes	213.75 KB	213.75 KB	0 bytes

➡️ SDK size impact change is minimal.

Raw measurements

Target branch:

{"baseline_dex_bytes": 0, "baseline_download_bytes": 2512, "baseline_install_bytes": 7528, "core_dex_bytes": 218884, "core_download_bytes": 122936, "core_install_bytes": 130189}

This PR:

{"baseline_dex_bytes": 0, "baseline_download_bytes": 2511, "baseline_install_bytes": 7528, "core_dex_bytes": 218884, "core_download_bytes": 122933, "core_install_bytes": 130183}

_{Measured 6486216 merged into b620b9b}

[github-actions]

📦 SDK Size Impact Report

What the SDK adds to a minified release APK.

Measured against a Compose + Material3 reference app, so these are the costs on top of an app that already ships Compose. The reference app's dependencies are a documented convention, not a measured average: see size-report-rokt/README.md.

mParticle Core + Rokt kit

Metric	Target branch	This PR	Change
APK size	1.31 MB	1.31 MB	0 bytes
Download size	1.29 MB	1.29 MB	+1 bytes
Dex bytes	2.33 MB	2.33 MB	0 bytes

Rokt SDK+ umbrella (adds the payment extension)

Metric	Target branch	This PR	Change	On top of mParticle Core + Rokt kit
APK size	6.55 MB	6.55 MB	0 bytes	+5.24 MB
Download size	6.44 MB	6.44 MB	+2 bytes	+5.14 MB
Dex bytes	7.13 MB	7.13 MB	0 bytes	+4.80 MB

➡️ SDK size impact change is minimal.

Raw measurements

Target branch:

{"baseline_dex_bytes": 1829108, "baseline_download_bytes": 1240062, "baseline_install_bytes": 1300934, "kit_dex_bytes": 4274892, "kit_download_bytes": 2596898, "kit_install_bytes": 2674686, "sdkplus_dex_bytes": 9305380, "sdkplus_download_bytes": 7989542, "sdkplus_install_bytes": 8165359}

This PR:

{"baseline_dex_bytes": 1829108, "baseline_download_bytes": 1240062, "baseline_install_bytes": 1300934, "kit_dex_bytes": 4274892, "kit_download_bytes": 2596899, "kit_install_bytes": 2674686, "sdkplus_dex_bytes": 9305380, "sdkplus_download_bytes": 7989544, "sdkplus_install_bytes": 8165359}

_{Measured b7711a1 merged into 4ee3ba4}

[cursor]

PR Summary

Low Risk
Test fixture and CI build configuration changes only; no runtime SDK code is modified.

Overview
Adds compile-only consumer fixture modules (compat/java-consumer and compat/kotlin-consumer) in a standalone settings-compat.gradle to verify the public API and kit interfaces against published release artifacts.

Both fixtures resolve com.mparticle dependencies exclusively from mavenLocal() at the target build version. The Kotlin fixture enforces allWarningsAsErrors to catch deprecations, nullability discrepancies, or R8 obfuscation issues that could break downstream consumers.

Integrates a new fixture build step into the CI pull-request.yml workflow under the Kit Compatibility Test job.

^{Reviewed by Cursor Bugbot for commit 6486216. Bugbot is set up for automated code reviews on this repo. Configure here.}