B: 2 - ui/common/BaseFragment.java

BaseFragment.java

public abstract class BaseFragment extends Fragment implements HasFragmentInjector {
    ...
    @Nullable
    private Unbinder viewUnbinder;
  
    @SuppressWarnings("ConstantConditions")
    @Override
    public void onViewStateRestored(Bundle savedInstanceState) {
        super.onViewStateRestored(savedInstanceState);
        // No need to check if getView() is null because this lifecycle method will
        // not get called if the view returned in onCreateView, if any, is null.
        viewUnbinder = ButterKnife.bind(this, getView());
    }
    
    @Override
    public void onDestroyView() {
        // This lifecycle method still gets called even if onCreateView returns a null view.
        if (viewUnbinder != null) {
            viewUnbinder.unbind();
        }
        super.onDestroyView();
    }
    
    ...
}