As many may have this question, I found that REST API version 2019-07 does not return the next or previous pagination URL.
All I get is:
X-Shopify-API-Version: 2019-07 Link: ; rel="next"
The url call is: /admin/api/2019-07/products.json?limit=2&published_status=published
I get 2 products, but the header does not give me the next url.