I'm rusty but I wanted to share something 

I did 

MooseModel allInstances second allModelClasses numberOfLinesOfCode

and I got an error because a group does not know number of lines of code.

It is better to do MooseModel root than allInstances when the model is installed in the Moose Panel (you can do it by performing #install on an instance of a MooseModel).

Why a FamixClassGroup does not know this message?

In fact it knows totalNumberOfLinesOfCode

But numberOfLinesOfCode is defined on model.

So is there a way to convert a group into a model?

Don’t do that. I migrate the numberOfLinesOfCode to AbstractMooseGroup and deleted totalNumberOfLinesOfCode which is now in duplication of numberOfLinesOfCode.

Vincent

Stef