BindingActivityModule.kt

@Module
abstract class BindingActivityModule {
    /**
     * ContributesAndroidInjector is including fragment injector. Only putting FragmentBindModule in modules array,
     * the children fragment can obtain the parent's fragment injector.
     */
    @PerActivity
    @ContributesAndroidInjector(modules = arrayOf(BindingFragmentModule::class))
    abstract fun contributeMainActivityInjector(): MainActivity
}