How to upload dependencies artifacts of a maven project to GitLab Package Registry?

There is a requirement of no Internet Access. As such, dependencies of a project need to be uploaded to GitLab Package Registry as part of the initial setup. Following the guide here: GitLab Maven Repository | GitLab I am able to deploy a Java project and push the resulting artifact to GitLab Package Registry. But how do I push all of the dependencies artifacts of this Java project to GitLab Package Registry?