https://adtmag.com/articles/2019/01/10/documentdb.aspx

Simmering tension between the open source community and increasingly dominant cloud platforms came to light with the introduction of the new DocumentDB managed service by Amazon Web Services Inc. (AWS), which uses open source MongoDB code.

Complaints and objections started soon after AWS announced the new managed Amazon DocumentDB service yesterday. Many addressed the issue of major cloud players like AWS infringing upon open source projects -- or their commercial backers -- by using their code as the base of optimized, proprietary cloud services.