Build with Java 10, but target 8 in Tika 2.0?

[Tim Allison]

All,
  What would you think of requiring Java 10 to build Tika 2.0 but still
setting 8 as the target?  This would allow us to bake modularity in now.
Given that I haven't actually tried modularizing/jigsawizing Tika yet, this
could be a complete disaster, of course. :)

         Cheers,

                  Tim