What I know that I do want, is that the Java I use to run maven/Tycho shouldn't have anything to do with what is used for compilation..
This is the purpose of setting useJDK=BREE and using toolchains that's been in Tycho for many years. This doesn't change.
And the recent change also goes in that directly, by totally uncoupling the source/target levels from running JRE.
Note that useJDK=SYSTEM (default) has always resolved dependencies against you current JRE. This also won't change with the proposal.
I do want that java8 jre/lib is used for compilation (so our bree). Because I really want to make sure we suddenly are not using API that is not there yet. Source/target level doesn't say much in this regard.
But as long as it works exactly as in eclipse it self I am fine.
useJDK=BREE at your rescue, it's similar to handling of multiple JREs in the IDE.
However, the default is still (and will remain) SYSTEM, which is like the Eclipse IDE, but with a single JRE defined (ie Java 11 APIs can leak as visible in Java 11 projects)
So I can run eclipse with java14 and inside eclipse I have configured a java8 and the compiler compiled against that one because that's the plug-in jre target
I don't think my proposal makes it worse in both case (useJDK=SYSTEM or useJDK=BREE)
