ViewModelModule - Module to bind your ViewModels. We also bind our custom ViewModelFactory here.

ViewModelModule.java

@Module
public abstract class ViewModelModule {
    @Binds
  @IntoMap
  @ViewModelKey(SplashScreenViewModel.class)
  abstract ViewModel bindSplashScreenViewModel(final SplashScreenViewModel splashScreenViewModel);

  @Binds
  @IntoMap
  @ViewModelKey(LoginActivityViewModel.class)
  abstract ViewModel bindLoginActivityViewModel(final LoginActivityViewModel loginActivityViewModel);

  @Binds
  @IntoMap
  @ViewModelKey(RegistrationViewModel.class)
  abstract ViewModel bindRegistrationViewModel(final RegistrationViewModel registrationViewModel);

  @Binds
  @IntoMap
  @ViewModelKey(HomeScreenViewModel.class)
  abstract ViewModel bindHomeScreenViewModel(final HomeScreenViewModel homeScreenViewModel);
  
  // Binding our own custom ViewModelFactory impementation here.
  @Binds
  abstract ViewModelProvider.Factory bindViewModelFactory(final CustomViewModelFactory factory);
}