javadoc:javadoc needs access to generated sources

currently, maven-model will not generate apidocs by simply calling javadoc:javadoc. This is because maven-model's sources are generated, and the javadoc report doesn't ensure that the 'generate-sources' phase is called.

However, when I changed the report to have:

@execute phase="generate-sources"

It still doesn't work. I suspect this may be because it's forking a new lifecycle and cloning the project to call generate-sources, which means the report doesn't use the right project instance to create the report. However, I've been unable to inject $

as a parameter; it fails the build, saying I need to supply that parameter on the command line.

I haven't committed any code changes to this report, since I don't currently have time to debug it properly, and I obviously haven't solved the problem.