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🔧 - Migrate zstandardandroid plugin from KGP to builtin Kotlin #142
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Is there an existing issue for this?
- I have searched the existing issues.
What area does this task affect?
Zstandard Android
Task description
I am using zstandard_android in my Flutter app.
Starting with Android Gradle Plugin (AGP) 9.0,
support for applying the Kotlin Gradle Plugin (KGP) has been removed.
Because this plugin applies KGP,
it causes a compilation error that prevents my app from building.
Flutter issue #181383
includes an example of the error.
Flutter has temporarily added support to allow KGP
while apps and plugins migrate to AGP 9.0 or later,
but this support will be removed in a future version of Flutter.
Please migrate this plugin to use built-in Kotlin to
ensure your plugin users can successfully
build their apps in future versions of Flutter.
Here is the Flutter
migration guide for plugin authors.
Current issues or inefficiencies
Kotlin Gradle Plugin (KGP) instead of Built-in Kotlin is used.
Expected impact
Future versions of Flutter will deprecate Kotlin Gradle Plugin (KGP), apps using zstandard_android will fail to build.
Alternatives considered
No response
Additional context or comments
No response
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[-]Migrate zstandard_android plugin from KGP to built-in Kotlin[/-][+]🔧 - Migrate zstandardandroid plugin from KGP to builtin Kotlin[/+]vypbot commentedon Aug 14, 2026
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Migrate zstandard_android plugin from KGP to built-in Kotlinto🔧 - Migrate zstandardandroid plugin from KGP to builtin Kotlin.Todo.P2in vypdev.zstandard_android/android/build.gradle:28applieskotlin-androidunconditionally, declares KGP on the buildscript classpath (:16), and useskotlinOptions(:60-62). The example apps (zstandard_android/exampleandzstandard/example) also apply KGP. This breaks builds under AGP 9.0+, which removes KGP support.Below are the recommended implementation steps, following Flutter's migration guide for plugin authors.
Migrate
zstandard_androidto built-in Kotlin (AGP 9+)1. Confirm the current state and choose a migration path
zstandard_android/android/build.gradle:16—classpath("org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version")zstandard_android/android/build.gradle:28—apply plugin: "kotlin-android"zstandard_android/android/build.gradle:60-62—kotlinOptions { jvmTarget = JavaVersion.VERSION_1_8 }< 9; use built-in Kotlin on AGP>= 9. Backward compatible with existing AGP 8 users.2. Update
zstandard_android/android/build.gradle(core fix)Apply the plugin conditionally and replace
kotlinOptionswith the moderncompilerOptionsDSL. Keep everything else (NDK, CMake, minSdk) unchanged.Also update the
buildscriptblock:2.0.0or later (ext.kotlin_version = "2.1.0") — thecompilerOptionsDSL requires KGP 2.0+, and this version is what the AGP< 9fallback path needs.9.x) the AGP classpath so the plugin still builds standalone and to exercise the AGP 9 path in tests.kotlin {}block noting it mirrorskotlinOptionsatJVM_1_8to match thecompileOptions(JVM 17 is only needed if you also raisecompileOptions).3. Bump minimum Flutter/Dart versions in
pubspec.yamlPer the guide, the
kotlin { compilerOptions {} }DSL requires KGP 2.0.0, which only arrives with Flutter 3.44. Updatezstandard_android/pubspec.yaml:8-10:docs/development/release-process.md), so plan a MINOR release (e.g.1.6.0) acrosszstandard_android,zstandard(which depends onzstandard_android), and the other federated packages so pub can resolve the new minimums.4. Migrate the example apps (app-developers migration)
Both example apps still apply KGP and must be migrated, since the plugin's own build is exercised through them:
zstandard_android/example/android/settings.gradle:19-23— bump AGP to9.xand drop the KGP plugin declaration:zstandard_android/example/android/app/build.gradle:1-6— removeid "kotlin-android"and thekotlinOptionsblock (:18-20); add thekotlin.compilerOptions {}block if you need to pin the target:zstandard_android/example/android/gradle.properties— add to enable/validate built-in Kotlin (requires Flutter 3.47+):android.builtInKotlin=trueApply the same four changes to
zstandard/example/android/(settings.gradle,app/build.gradle,build.gradle,gradle.properties) since the main package's example also applies KGP.5. Update the CHANGELOG
Add an entry at the top of
zstandard_android/CHANGELOG.md(and the rootCHANGELOG.md, which is copied per package on release):6. Validate locally
flutter analyzeinzstandard_androidandzstandard.flutter testinzstandard_android(unit tests).zstandard_android/example, run the integration tests on an emulator:flutter test integration_test/ -d emulator-55549.x,android.builtInKotlin=true, on Flutter3.47+.8.xand KGP2.0+to confirm the conditional branch still applies KGP and builds.7. Update CI
pr_check_android.ymlcurrently pinsFLUTTER_VERSION: '3.41.4'(:14), which predates the changes. Update it to3.47+ (or add a version matrix covering both the old and new Flutter/AGP combos) so the emulator integration tests in that workflow exercise the migrated build. Keep the pub-cache variant (check_android_test_from_pub_cache) as-is.8. Documentation
docs/platforms/android.mdmentioning thatzstandard_android1.6.0+ requires Flutter 3.44+ and works with both AGP 8 (via KGP) and AGP 9+ (built-in Kotlin).Notes / caveats
build.gradlebuildscriptblock only affects standalone/Android-Studio builds; when consumed by an app, the app's AGP/KGP classpath governs theagpMajorcheck, which is exactly what the conditional logic keys on.jvmTargetaligned withcompileOptions(1.8); only bump toJVM_17if you also raisecompileOptions, which is a larger breaking change and not required for this issue.zstandard_androidminimum consistently withzstandard.Debug log
🚀 Happy coding!
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efraespada commentedon Aug 20, 2026
This will be fixed on a couple of days. Thanks for reporting @maximilianoe
maximilianoe commentedon Sep 1, 2026
@efraespada In case you can't handle this at the moment, please add me as collaborator and I will open the PR.
efraespada commentedon Sep 2, 2026
Temporary workaround until the next pub.dev release:
The Built-in Kotlin migration for this issue is now available on the
masterbranch.To consume the fixed Android package from this repository:
If the application depends on the federated
zstandardpackage, overriding only the root package does not replace its transitive platform package, sozstandard_androidmust be overridden explicitly.Switch back to the published package when the next release is available.