[regression] Optional flag from dependency management applied to dependencies

The situation is quite complex to explain. I've a parent pom that defines dependencies in depMgmt. There's two projects in the multimodule project, the second depending on the first.

Excerpt (parent/depMgmt):
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<version>$

</version>
<scope>runtime</scope>
<optional>true</optional>

First child (redefines scope only):
<dependency>
<groupId>ch.qos.logback</groupId>
<artifactId>logback-classic</artifactId>
<scope>compile</scope>
</dependency>

Second child:
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
</dependency>
<dependency>
<groupId>m3pb</groupId>
<artifactId>subproject1</artifactId>
<version>$

</version>
</dependency>

When running with maven 2, it works. When ran with maven 3, it fails on the second project, with a NoClassDefFoundError on the logback jar.

I seem to understand this is actually a bug in maven 2: as the depMgmt defines optional=true, it shouldn't have been working in maven2 without redeclaring the dependency in the second project.

From my understanding:

• With maven 2, the transivity is taken in account and gives logback through the subproject1 link (from the second)
• With maven 3, this just doesn't work and this is the correct behaviour.

Please excuse my basic analysis.
I'm attaching a test project to let see more precisely the problem.

If you need any help, please let me know.

Cheers
-- 
Baptiste