Again this is all wild assumption. They're not required to contribute to free software, but they do upstream changes. The improvements they're claiming is for

Again this is all wild assumption. They're not required to contribute to free software, but they do upstream changes. The improvements they're claiming is for their own EMR product, not to Spark, and they do make updates to software to run better on their own own infrastructure. That's what their customers care about. You seem dedicated to believing that Amazon has done nothing for open-source even I pointed you to an exhaustive list of their contributions. At this point, there's nothing more to say.