Restrictions on service loading

[David M. Lloyd]

It doesn't seem clear whether this is a spec or implementation issue, so 
I'm posting here to start.

The gist of the problem is, code running in a module cannot use 
ServiceLoader to find things that it hasn't been declared to "use" even 
if a target class loader is specified.  This doesn't really make a lot 
of sense because in the case where you're specifying a class loader, you 
are pretty clearly establishing that you want to search the class 
loader, not a module space.

This can be worked around by adding a "uses" at run time, but it 
shouldn't be necessary for the explicit class loader case.
-- 
- DML