A custom Application which include Multidex and Flutter initialization

CustomApplication.kt

package com.example

import android.app.Activity
import android.app.Application
import android.content.Context
import android.support.multidex.MultiDex

import io.flutter.view.FlutterMain

class CustomApplication : Application() {
    override fun attachBaseContext(base: Context) {
        super.attachBaseContext(base)
        MultiDex.install(this)
    }

    override fun onCreate() {
        super.onCreate()
        FlutterMain.startInitialization(this)
    }

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

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