What is the proper file structure of a module that only contains sub-modules? I have put together a module package that has 3 sub-modules. They must be contained in a single folder to be distributed and used by other devs. Are there drupal best practices for how a module's files structure should be if it contains just multiple modules?

e.g.  

name_of_module/modules/module1/module1.info
name_of_module/modules/module2/module2.info
name_of_module/modules/module3/module3.info


or

name_of_module/module1/module1.info
name_of_module/module2/module2.info
name_of_module/module3/module3.info


or?
For what i've seen, putting sub modules in a modules folder like your first example is most common best practice.