So, from now on, each gerrit/jenkins build will execute also those
tests that require JDK 9 (variable isJRE9 and similar).
While finalizing this I observe strange differences betweeen versions
os JDK 9: among two installations of 9+181 and on installation of 9.0.1
I observed three different sets of included modules.
Tests now detect which exact version they run on, and select their
expectations based on that, but if equal version still doesn't guarantee
equal content this can cause your local tests to fail.
The tests to watch out for are: JavaProjectTests.testBug522554_*.
If you locally observe failures in any of these, please drop a comment in
https://bugs.eclipse.org/522554 mentioning the exact JDK version.