Android : How to selectively decorate RecyclerView items

I am creating a subclass of ItemDecoration from this gist: https://gist.github.com/alexfu/0f464fc3742f134ccd1e

How to make it only decorate items with certain condition? For instance, only decorate items with certain positions, type of ViewHolder, etc.

I have modified the above mentioned gist (plus some changes on deprecated Android API) with this code, but all items get decorated anyway:

public boolean isDecorated(View view, RecyclerView parent) {
    RecyclerView.ViewHolder holder = parent.getChildViewHolder(view);
    return holder instanceof MenuIconViewHolder || holder instanceof MenuDetailViewHolder;
}

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
    if (isDecorated(view, parent)) {
        if (mOrientation == VERTICAL_LIST) {
            outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
        } else {
            outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
        }
    } else {
        super.getItemOffsets(outRect, view, parent, state);
    }
}

What's wrong with above code? By the way, can it be considered best practice (in respect of separation of concerns) to place that kind of code in ItemDecoration class?