8233922: Service binding augments module graph with observable incubator modules

[Alex Buckley]

On 11/18/2019 4:34 AM, Alan Bateman wrote:
> The summary on this issue is that service binding augments the
> module graph with the modules induced by the service-use relation.
> ... If service binding were to resolve `jdk.incubator.jpackage`  > then a warning would be emitted in all phases that java.base
> is resolved (so everywhere).
> 
> ... The change proposed here means that incubator modules are not 
> candidates to add to the module graph during service binding for the
> boot layer's configuration. It has no impact on the general case 
> where incubating modules may be observable when creating the 
> configuration for custom layers.
An incubator module's service providers will now be unavailable by 
default even if a module on the module path says `uses`. I believe that 
JEP 11 should say the following:

-----
Incubator modules are part of the JDK run-time image produced by the 
standard JDK build. *****However, by default, incubator modules are not 
resolved for applications on the class path. Furthermore, by default, 
incubator modules do not participate in service binding for applications 
on the class path or the module path.*****

Applications on the class path must use the --add-modules command-line 
option to request that an incubator module be resolved. Applications 
developed as modules can specify `requires` or `requires transitive` 
dependences upon an incubator module directly. *****(Some incubator 
modules do not export packages but rather provide implementations of 
services. It is usually not recommended to require a module that exports 
no packages, but it is necessary in this case in order to resolve the 
incubator module and thus have it participate in service binding.)*****

During the JDK build, incubator modules must be packaged ...
-----

Alex