Switch to parametric CI jobs. Given the changes in CI this also switches to running Gradle with the build java version only ( we used to also run it with run-time java version )
Now that JDK 11 is GA, we would switch our 6.x and master branches to
the JDK 11 compiler. This commit makes this change, as well as removes
JDK 10 from the CI configuration.
* Add test matrix axis files for periodic java testing
* Add properties file defining java versions to use
* We have no openjdk8
* Remove openjdk
Oracle Java and OpenJDK basically only differ in license, so we don't
need to test both.
Alpar Torok
Jason Tedor
David Leatherman