The references to github in that document are examples only. You don't require a github clone to contribute to an Eclipse project. When using git, the expectation is that the first thing you do is to make your own clone of the repository. That clone does not have to be at github. See  for a set of example workflows written by the Eclipse Platform team as they migrated from CVS to git.
For advice on using git, you can also ask git@xxxxxxxxxxx. The ebook at  has a lot of useful information as well.
The EclipseLink project may also want to consider making use of Gerrit. Other projects at Eclipse have adopted it with great success as a tool for reviewing and approving contributions to their projects.
I hope that helps.
From: eclipselink-dev-bounces@xxxxxxxxxxx [mailto:eclipselink-dev-bounces@xxxxxxxxxxx] On Behalf Of Heider, Sabine
Sent: August-16-12 5:39 AM
Subject: [eclipselink-dev] GitHub mirror for eclipselink.runtime and incubator
Hi Eric, hi all,
I’ve been trying to understand how the contribution process is supposed to work with the new Git repositories. This page describes how to contribute using a GitHub repository: http://wiki.eclipse.org/Development_Resources/Handling_Git_Contributions
I have to add that I’m a Git newbie, so I might be wrong, but I got the impression that the entire process only works if there is a mirror of the official EclipseLink Git repositories hosted by GitHub. EclipseLink repositories are currently not mirrored, though – at least I didn’t find them in this list: https://github.com/eclipse.
Could you please have the eclipselink.runtime repository and the incubator repository (and maybe also the others) mirrored as well? According to page http://wiki.eclipse.org/Git/GitHub it seems that it’s not a big deal (I hope).
Thanks and best regards,