Fred:he is missing slf4j-nop as a runtime dependency specifically:
<dependency> <groupId>org.slf4j</groupId>
<artifactId>slf4j-nop</artifactId>
<version>1.7.2</version> <scope>runtime</scope>
</dependency>
Martin--
______________________________________________
> From: fred.co...@gmail.com
> Date: Mon, 15 Aug 2016 22:13:45 +1200
> Subject: Re: slf4j runtime dependency for plugin
> To: dev@maven.apache.org
>
> Clearly it's going to matter to him if Maven fails to provide and it
> doesn't work. Some sort of dependency isolation not right somewhere?
> Something seems to be going on. You're right, but he's seeing behaviour
> that indicates something is amiss.
>
> On Mon, Aug 15, 2016 at 6:37 PM, Michael Osipov <micha...@apache.org> wrote:
>
> > Am 2016-08-14 um 23:21 schrieb Christopher:
> >
> >> On Sun, Aug 14, 2016 at 4:31 PM Michael Osipov <micha...@apache.org>
> >> wrote:
> >>
> >> Am 2016-08-12 um 23:48 schrieb Christopher:
> >>>
> >>>> Hi,
> >>>>
> >>>> I use a plugin which has a runtime dependency on an slf4j
> >>>> implementation,
> >>>> but the plugin itself is built without declaring one in its pom. (
> >>>> https://github.com/koraktor/mavanagaiata/issues/43)
> >>>>
> >>>> In some versions of Maven, I get a warning about slf4j not finding an
> >>>> implementation. In other versions, it is silent.
> >>>>
> >>>> Was an slf4j implementation provided in newer versions to the execution
> >>>>
> >>> of
> >>>
> >>>> plugins?
> >>>>
> >>>> Will there be a multiple-binding conflict if the plugin itself provides
> >>>>
> >>> one
> >>>
> >>>> of its own to get rid of the warning on certain versions of maven which
> >>>> result in that warning (I didn't see one when I tried)?
> >>>>
> >>>> If there is a risk of a conflict, which implementation would be
> >>>> preferred
> >>>> in order to converge on one provided by Maven?
> >>>>
> >>>> Is there another solution the plugin should seek?
> >>>>
> >>>> In general, what dependencies are plugins expected to provide, and what
> >>>> dependencies are expected to be provided by Maven, and how are conflicts
> >>>> resolved in the architecture?
> >>>>
> >>>> Feel free to comment on the GitHub issue directly, or here. I'll be
> >>>> watching both.
> >>>>
> >>>
> >>> I will cite what I have written on Stack Overflow
> >>> (http://stackoverflow.com/a/7107934/696632) five years ago and it still
> >>> holds true:
> >>>
> >>> You *never* provide a log implementation. The client application has to
> >>> do so. Otherwhise this would be a violation of separation of concerns.
> >>> Don't do any assumptions about an unknown client.
> >>>
> >>>
> >>> I agree with that sentiment...generally. But this is a maven plugin, so
> >> I'm
> >> trying to figure out what Maven is going to provide it when it executes.
> >> If
> >> it's not going to provide an implementation, then the plugin has to. If
> >> you
> >> have answers to the specific questions I asked above, I think it might
> >> help.
> >>
> >
> > It should not matter to you what Maven provides. It will always provide
> > some backend. Otherwise Maven won't be able to log itself. Even if Maven
> > would not provide anything. It is not your task to force some
> > implementation. It is a several failure of the client to do so.
> >
> > Michael
> >
> >
> >
> > ---------------------------------------------------------------------
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> >
> >
