Maven 3: Generate Javadoc for defined artifacts

Question

I want to generate javadocs only for certain artifacts of my project from within a dedicated docs-project.

That means that I would like to have an independent project called "docs" for example. In the docs/pom.xml I would like to define the artifacts that should be included in the generated javadocs.

So far I learned that I have to generate a separate sources.jar for the projects I want to include. But I can't figure out how to go on from there.

For now I can only imagine two approaches:

1. Get the artifacts (sources.jar) I want to include, unpack them and somehow point the Javadoc plugin to the source directory.

2. Define the artifacts I am interested as dependency and use the "dependencySourceInclude" option of the javadoc-plugin. But I am not sure if this is usage as intended.

Any suggestions how to solve this problem?