Well, I try to be a bit more specific what is the idea behind this issue:
The docker-commons-plugin provides a section in the global configuration of the Jenkins where you can configure your default docker registry (= override docker hub). But this has no effect to any of the workflow steps provided by this plugin. To use a different different registry than docker hub you have to use the docker.withRegistry step of this plugin.
In our case we have just one docker registry where all docker images that the Jenkins requires come from and the dockerd of the Jenkins doesn't have access to the internet at all which means no access to docker hub. At the moment we have to surround all our build steps that need a docker image with the same docker.withRegistry step again and again. In this case it would be nice if we could do this just by configuring our docker registry in the global configuration of the Jenkins and that's it.
I hope this makes it more clear what's the intention behind this issue.