javac knows if a module is an automatic module. We should expose that through the Elements class. 

For example:

    public boolean isAutomaticModule(ModuleElement me) {
        if (me == null) {
            return false; // or throw NPE
        } else {
            ModuleSymbol msym = (ModuleSymbol) me;
            return (msym.flags() & Flags.AUTOMATIC_MODULE) != 0;
        }
    }