Proposal: #ExportAnnotation

[mark.reinhold at oracle.com]

Issue summary
-------------

  #ExportAnnotation -- Define a standard, source-retention `Export`
  annotation which can be used in a `package-info.java` file to indicate
  that the package is to be exported.  Tools that create
  `module-info.java` files could then interpret this annotation in order
  to generate corresponding `exports` clauses.  [1]

Proposal
--------

Do not implement this feature.

The declaration of a module is centralized in a single file in order to
make it easy to see exactly what a module exports, requires, uses, and so
forth.  Distributing package-export information across a module's
`package-info.java` files would just make the related `module-info.java`
file more difficult to read.  This is not a practice that we should
encourage.

If someone really wants to do this then they can easily define their own
annotation for this purpose.


[1] http://openjdk.java.net/projects/jigsaw/spec/issues/#ExportAnnotation