Yes it's down to classloading - the extension and plugin have different classloaders and the InfoHolder class loaded by the extension is different to the one loaded by the plugin. They may share the same name and have the same original bytecode, but they were defined by different classloaders. You can see this by adding a constructor to InfoHolder and printing out its classloader (you can also print the class' hashcode to show it really is a different class, just with the same name.)
To share the extension class with the plugin you'll need to add an extension descriptor to the jar: https://maven.apache.org/ref/3.6.0/maven-core/extension.html But you'll also need to solve a second issue which comes down to the fact you're using the same jar as an extension and a plugin - the component metadata is going to be registered in both places, which will still lead to two separate copies (each component will be a singleton in its own 'realm' governed by the component metadata.) I would recommend using two separate projects - one for the extension and one for the plugin. The extension project will have the component and the extension descriptor, while the plugin project will just have the mojo and depend on the extension project. On Thu, 4 Feb 2021 at 20:40, Matthieu Brouillard <matth...@brouillard.fr> wrote: > Hum some words have disappeared from my previous mail. > The project URL is https://github.com/McFoggy/maven-jsr330-demo > <https://github.com/McFoggy/maven-jsr330-demoYou>. > And the corrected sentence is: You will see that the project is simple... > Sorry for the double post. > > > On Thu, Feb 4, 2021 at 9:27 PM Matthieu Brouillard <matth...@brouillard.fr > > > wrote: > > > Hi all, > > > > As I was trying to cleanup & simplify my plugins by moving to JSR330, I > > came across a weird use case in which a `@Singleton` object exists > multiple > > times (several instances) during the build: > > - it is first used by an extension, to store some value > > - then used in a mojo to retrieve and print the value > > > > Before opening an issue, I wanted to be sure that I did not make some > > errors in the simplified project and that my expectations of how it > should > > work are OK. > > > > I pushed a simplified project with README here: > > https://github.com/McFoggy/maven-jsr330-demoYou will that the project is > > simple: > > - the @Singleton information store > > - the extension filling the store > > - the mojo > > > > Thanks for any enlightenment. > > > > PS: can the issue come from different classloaders being probably used? > > > > Matthieu > > >
