AGP 9 built-in Kotlin: remove unconditional kotlin-android apply

[TN19N]

Problem

Flutter 3.44 / Android Gradle Plugin 9+ deprecated the standalone Kotlin Gradle Plugin (KGP) in favour of AGP's built-in Kotlin support (android.builtInKotlin=true, the default on AGP 9+).

This plugin currently applies kotlin-android unconditionally in its Android build file, e.g.:

apply plugin: 'kotlin-android'

Apps on AGP 9+ work today because the Flutter tool temporarily adds android.builtInKotlin=false as a compatibility shim (flutter/flutter#181383), but this shim is scheduled for removal before AGP 10. When removed, any plugin still applying kotlin-android unconditionally will break the Android build.

Suggested fix

Guard the apply with an AGP version check, the same pattern used by device_info_plus, package_info_plus, and share_plus:

// build.gradle.kts
val agpMajor = com.android.Version.ANDROID_GRADLE_PLUGIN_VERSION.split(".").first().toInt()
if (agpMajor < 9) {
    apply(plugin = "org.jetbrains.kotlin.android")
}

Groovy equivalent:

def agpMajor = com.android.Version.ANDROID_GRADLE_PLUGIN_VERSION.split("\\.")[0].toInt()
if (agpMajor < 9) {
    apply plugin: 'kotlin-android'
}

References

• Flutter tracking issue: flutter/flutter#181383
• Flutter built-in Kotlin migration guide for plugin authors: https://docs.flutter.dev/release/breaking-changes/migrate-to-built-in-kotlin/for-plugin-authors