Migrate Application from Java to Kotlin

Java codes:

public class DemoApplication extends DaggerApplication {
    private static DemoApplication sApplication;

    public DemoApplication() {
        sApplication = this;
    }

    public static Context getAppContext() {
        return sApplication.getApplicationContext();
    }
}

Kotlin codes:

// top level properties
private lateinit var sApplication: DemoApplication

val appContext: Context
    get() = sApplication.applicationContext

class DemoApplication : DaggerApplication() {
    init {
        sApplication = this
    }
}