A: 7 - AppModule.java

AppModule.java

@Module(includes = AndroidInjectionModule.class,
        subcomponents = {
                MainActivitySubcomponent.class,
                Example1ActivitySubcomponent.class,
                Example2ActivitySubcomponent.class
        })
abstract class AppModule {

    ...

    // TODO (ContributesAndroidInjector) remove this in favor of @ContributesAndroidInjector
    @Binds
    @IntoMap
    @ActivityKey(Example2Activity.class)
    abstract AndroidInjector.Factory<? extends Activity>
    example2ActivityInjectorFactory(Example2ActivitySubcomponent.Builder builder);
}