[Feature Request] Support Gradle 9.x / AGP 9.x compatibility

[chico0920]

Environment

• flutter_boost version: 5.0.2
• Flutter version: 3.35.0+ (Kotlin-based Gradle plugin)
• Gradle version: 9.2.0
• AGP version: 8.10.1 / 9.0.0
• OS: macOS

Description

When using Gradle 9.x (which bundles Groovy 4 and Kotlin 2.2), the project fails to configure the :flutter_boost module with a NullPointerException:

A problem occurred configuring project ':flutter_boost'.

Failed to notify project evaluation listener.
java.lang.NullPointerException (no error message)
at com.flutter.gradle.FlutterPluginUtils.getAndroidExtension$gradle(FlutterPluginUtils.kt:391)
at com.flutter.gradle.FlutterPluginUtils.getCompileSdkFromProject(FlutterPluginUtils.kt:405)
at com.flutter.gradle.plugins.PluginHandler$Companion$configurePluginProject$2.execute(PluginHandler.kt:143)

Root Cause

Flutter 3.32+ converted the Gradle plugin from Groovy to Kotlin. The new PluginHandler tries to call getAndroidExtension() on the flutter_boost plugin project during afterEvaluate, but the Android extension is null at that point — likely because flutter_boost's build.gradle does not apply the Android library plugin in a way that is compatible with the new Flutter Kotlin Gradle plugin's evaluation order.

Expected Behavior

flutter_boost should be compatible with:

• Gradle 9.x (Groovy 4, Kotlin 2.2)
• Flutter 3.32+ (Kotlin-based Gradle plugin)
• AGP 9.x (new DSL)

Workaround

Currently the only workaround is to downgrade to:

• Flutter ≤ 3.29.x (Groovy-based Gradle plugin)
• Gradle 8.x (Groovy 3)

Related

• Flutter AGP 9 migration guide: https://docs.flutter.dev/release/breaking-changes/migrate-to-agp-9
• Flutter Gradle 9 module issues: [Gradle 9] Flutter Module Template Has Deprecated Gradle Features flutter/flutter#181520