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From Anders Hammar <>
Subject Re: Duplicate plugin declaration warning
Date Tue, 23 Dec 2014 21:25:32 GMT
You don't bind a plugin to a phase but rather a plugin's goal. So it is
possible to do what you want by having just one plugin declaration but two
executions specified (for plugin A); one execution for goal A1 bound to the
generate-resources phase and one execution for goal A2 bound to the
process-resources phase. There's an example in [1].

The warning is a warning right now, it will still work. However, this
support can be removed in future versions of Maven.



On Tue, Dec 23, 2014 at 10:11 PM, David Hoffer <> wrote:

> I have some questions regarding the duplicate plugin declaration warning,
> e.g.
> [artifact:mvn] [WARNING] 'build.plugins.plugin.(groupId:artifactId)' must
> be unique but found duplicate declaration of plugin
> org.apache.maven.plugins:maven-xxx-plugin
> First is this a benign warning that can be ignored or is it really
> something that is not supported (multiple declarations of the same plugin)
> and that I really need to remove?
> If it's the later case this really limits the flexibility of plugins, let
> me explain with an example.
> If my current build does the following in order:
> Plugin A - Phase: generate-resources
> Plugin B - Phase: process-resources
> Plugin A - Phase: process-resources
> By defining plugin A twice I'm able to use the most appropriate phase for
> each instance of the plugin (btw, each instance has several executions).
> The key to the above is that plugin B has be be done between each of the
> two instances of plugin A.
> If I had to only have one plugin A I'd have to set the phase in the later
> case to something later than process-resources (or I'd have to adjust the
> first one to something earlier).  Not only does it make it harder to follow
> the flow (later in the pom is more clear) but it sometimes forces the use
> of poor phases as I have many other plugins in this pom after/before these
> that are tied to phases as well so it limits what can be chosen here to
> satisfy a no duplicate plugin rule.
> What's really the rule here regarding duplicate plugins?
> -Dave

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