How to setup Unsplash Grid Layout

private fun setupRecyclerView() {
    val gridLayoutManager = grid!!.layoutManager as GridLayoutManager?
    gridLayoutManager!!.spanSizeLookup = object : SpanSizeLookup() {
        override fun getSpanSize(position: Int): Int {
            /* emulating https://material-design.storage.googleapis.com/publish/material_v_4/material_ext_publish/0B6Okdz75tqQsck9lUkgxNVZza1U/style_imagery_integration_scale1.png */
            return when (position % 6) {
                5 -> 3
                3 -> 2
                else -> 1
            }
        }
    }
    grid!!.addItemDecoration(
        GridMarginDecoration(
            resources.getDimensionPixelSize(R.dimen.grid_item_spacing)
        )
    )
    grid!!.setHasFixedSize(true)
}

public class GridMarginDecoration extends RecyclerView.ItemDecoration {

    private int space;

    public GridMarginDecoration(int space) {
        this.space = space;
    }

    @Override
    public void getItemOffsets(Rect outRect, View view,
                               RecyclerView parent, RecyclerView.State state) {
        outRect.left = space;
        outRect.top = space;
        outRect.right = space;
        outRect.bottom = space;
    }
}