support for java9 (jigsaw)

[hohwille]

It was a design goal of jigsaw to allow creating modules that are still compatible with java8.
Though we still have to verify that in detail it seems promising and worth a try to prepare for jigsaw early on then.
However, currently jigsaw has strong limitiations such as no support for optional dependencies. Further it has a strong impact on reflection. If there is no movement and collaboration with feedback from (OSS) libraries in jigsaw and they just focus on staying in schedule IMHO jigsaw will be a dead animal from its birth. As it has great potential and also big projects such as spring are raising demands for optional dependencies we all hope for the best and expect some movement.

Insights:
https://github.com/ftrossbach/IntroToJigsaw

Maven-Support:
https://cwiki.apache.org/confluence/display/MAVEN/Java+9+-+Jigsaw