They don't upgrade the open source version because their internal version depends on that open source version and they don't can't upgrade internally to 2.12.
They can't upgrade because of several dependencies of their own, the last one Finagle.
All of those although "cross compiles are no problem" as the default answer from the Scala development team on these issues.
https://github.com/foursquare/fsqio/issues/37
They don't upgrade the open source version because their internal version depends on that open source version and they don't can't upgrade internally to 2.12.
They can't upgrade because of several dependencies of their own, the last one Finagle.
All of those although "cross compiles are no problem" as the default answer from the Scala development team on these issues.