How to change the owner of a plugin ?

Can anyone give some hint how to change the owner of a plugin listed on the Plugins Directory ?

I details we (Jost Baron and I) want to change the owner of redmine_workload to myself.

We already contacted maeda@farend.jp and jan.niggemann@redmine.org but got no awnser so far.

Who can help?
How can we contact redmine-admins regarding this topic?

Redmine