Jigsaw related questions emerged during Java 9 Jigsaw Hack Day

[Oleg Tsal-Tsalko]

Dear experts,

Recently we run Java 9 Jigsaw Hack Day in Kiev, Ukraine and several
questions have been raised:

   1. When declaring 'exports' in module descriptor why wildcard are not
   supported like com.abs.*?
   2. Why compilation doesn’t fail in case several modules with same name
   put on module-path, but it only fails in runtime on startup (
   https://github.com/AdoptOpenJDK/jdk9-jigsaw/tree/master/session-1-jigsaw-intro/08_ModulesExportConflict
   )?
   3. What is the best practice for using `transitive` dependencies? Where
   to use them apart of cases when type of one module are used in API of
   another module like return types, etc.?
   4. If there are 3 conflicting modules in module path error says only
   about 2 first modules conflict only. Why that? Fail fast?

Thank you,
Oleg