ActivityBuilder.java

@Module
public abstract class ActivityBuilder {

    @ContributesAndroidInjector(modules = LoginActivityModule.class)
    abstract LoginActivity contributeLoginActivity();

    @ContributesAndroidInjector(modules = {
            MainActivityModule.class,
            CategoryFragmentProvider.class,
            ProfileFragmentProvider.class,
            LeaderboardFragmentProvider.class})
    abstract MainActivity contributeMainActivity();
}