Oh thanks for the clarification, Jochen, I didn't realize the problem was with Maven itself. I think Maven over-interprets the spec. It's not because you find a file in `META-INF/services` that it *must* be a service descriptor.

Now for the extension mechanism, for sure we need to check what it means for us.

2017-12-04 10:23 GMT+01:00 Jochen Theodorou <blackdrag@gmx.org>:
Just to clarify things... This is a maven plugin complaining, not JDK9, as I see it. Afaik the plugin tries to create a module configuration for groovy and cannot interpret the services provided in those directories. JDK9 would not care, unless you say your module is providing a certain service.

And I want to add two more points: The extension mechanism is unlikely to work as intended on JDK9. If you want to provide a service across modules you are now forced to use the very doubtful ServiceProvider infrastructure. And one module to read a file from another module was at least till late stages of JDK9 not possible. I am not sure what the latest state here was. Maybe I did interpret something wrong - writing a test for this would be easy.

But if I am right, this would mean our extension mechanism must become a SPI structure to enable other modules to provide extension modules.

Am 03.12.2017 um 19:01 schrieb Cédric Champeau:
This file is used by Groovy internally, there's no reason for the JDK to interpret its contents since it has only a meaning for Groovy. In short, it declares the list of extensions recognized by the Groovy compiler. That it prevents loading as a module is rather strange.

2017-12-03 16:37 GMT+01:00 Ceki Gulcu <ceki@qos.ch <mailto:ceki@qos.ch>>:

    Hi all,

    Referring to a discussion on the maven users list [1], it appears that
    removing the file
    META-INF/services/org.codehaus.groovy.source.Extensions from
    groovy-2.4.13.jar allows Java 9 to successfully load
    groovy-2.4.13.jar as an auto-module.

    The org.codehaus.groovy.source.Extensions file contains the lone
    word "groovy" instead of a fully qualified class name.

    Please advise.

    Best regards,

    Ceki Gülcü

    [1] http://markmail.org/message/obdyvuv24kqpxm6v