Merging JDK9 branch to default

Hello,
NetBeans development team is merging today jet-main jdk9 branch into 
jet-main repo default. This will bring into NB9 daily development builds 
JDK9 multi module projects after changes propagate up to main-silver.
We tried to prepared this merge as well as possible. There can be some 
failures of build jobs in some other repos which we will be fixing after 
the merge. This could also take a while.
This should be the latest big merge into daily dev builds during NB9 
development.

Thanks' for understanding,
Martin