ExternalProject does not allow NOT to init all the submodules
This issue was created automatically from an original Mantis Issue. Further discussion may take place here.
Using the GIT_SUBMODULES
argument, it is possible to initialize and update only a subset of modules, but it is not possible to skip all of them
Passing GIT_SUBMODULES ""
or not passing GIT_SUBMODULE
at all is the same, and the behavior is to initialize and update ALL the submodules.