The Microsoft Build of OpenJDK is very much a build of OpenJDK that Azure customers can get free support for and over time get some Azure specific performance benefits from. Those performance benefits will be worked on upstream as well (like this escape analysis patch was) but there will be times where upstream won't want to take a patch on a stable LTS branch for example. We'll continue to be very clear when we have a patch that is not in the upstream code and it'll always be available on our GitHub under the GPLv2+CE license.
The Microsoft Build of OpenJDK is very much a build of OpenJDK that Azure customers can get free support for and over time get some Azure specific performance benefits from. Those performance benefits will be worked on upstream as well (like this escape analysis patch was) but there will be times where upstream won't want to take a patch on a stable LTS branch for example. We'll continue to be very clear when we have a patch that is not in the upstream code and it'll always be available on our GitHub under the GPLv2+CE license.