Couldn't you use git with submodules? e.g. In your .gitmodules file, you
may add this:
path = volley
url = https://path/to/volley/repository
You can set the url to Volley's official repository, or to your own
in-house version of volley. Other projects can be setup the same way and
point to the same volley repository.
I think this way, other users can call
git clone and all
the dependent projects will be downloaded within the main project folder
and they don't have to worry about downloading the library projects
For Volley though, I would just compile it into a JAR file and stick it
into the /libs folder of the main project. That is, if you don't need to
modify its source.
For library projects that you don't need to modify its source, you can try
using Android Studio to compile them into AAR files for sharing. AAR file
is like a JAR file to Android, so you can add them to your /lib source
folder, or publish them to your local/intranet maven repository. If you
choose the maven route, add your local/intranet repository in build.gradle,
and reference the library project that you've published.
Hopefully in the future more Library projects owner will build their
projects into AAR file and publish them to Maven Central Repository, so we
can just reference them directly from the build.gradle file.