如何在Flutter中创建自定义android应用程序类？

Question

class MyApplication : FlutterApplication() {


    @CallSuper
    override fun onCreate() {
        super.onCreate()
        AppSpector
                .build(this)
                .withDefaultMonitors()
                .run("***")
        FlutterMain.startInitialization(this)
    }

    private var mCurrentActivity: Activity? = null
    override fun getCurrentActivity(): Activity? {
        return mCurrentActivity
    }

    override fun setCurrentActivity(mCurrentActivity: Activity) {
        this.mCurrentActivity = mCurrentActivity
    }
}

我想使用自定义应用程序类。但是当其他活动启动时却出现错误 java.lang.IllegalArgumentException: Parameter specified as non-null is null: method kotlin.jvm.internal.Intrinsics.checkParameterIsNotNull, parameter mCurrentActivity