Bugzilla Bug 176182

Take for example jdbc drivers. The package can use these if they are installed
but there is no point in dependending on all of them. So I propose:
01:48 <@Betelgeuse> put OPTIONAL_DEPEND="" to package.env
01:48 <@Betelgeuse> gjl takes a look if it's installed
01:48 <@Betelgeuse> if it is, puts to cp
01:49 <@Betelgeuse> Should work with any provider type infra

The only problem I see with it that the package needs to know about all
existing providers and has to be updated if some new are added. Could also
think of some way there the providers would register by putting a file
somewhere, like ant-tasks register themselves.

(In reply to comment #1)
> The only problem I see with it that the package needs to know about all
> existing providers and has to be updated if some new are added. Could also
> think of some way there the providers would register by putting a file
> somewhere, like ant-tasks register themselves.
> 

Combine this with virtuals support and we should be all set.

(In reply to comment #2)
> Combine this with virtuals support and we should be all set.

Well if virtuals have support for "gimme all packages satisfying a virtual" and
not just one package :)

In java-config-2.0.33-r1 and eclass - new function
java-pkg_register-optional-dependency