Currently, using a Gmail account for the Hudson Jabber user, the Jabber plug-in will automatically authorize any user that tries to add the Hudson Jabber user to their contact list regardless of the Gmail account settings.
That is, under Gmail settings > Chat, if one selects the option "Only allow people that I've explicitly approved to chat with me and see when I'm online." for the Hudson Jabber user, the Jabber user will automatically approve the user bypassing the Gmail interface for approving the user by selecting "Yes" or "No".
You can see this happening if you are logged into the Hudson Jabber user's Gmail account and have someone try to add the user; in the chat window on the left-hand side of the screen, you'll see the Gmail prompt saying "[username] wants to be able to chat with you. Okay?" (See the attached image to see what this looks like) with two buttons "Yes" and "No", however within one second this prompt immediately disappears before you take an action and the user is added to the contact list.
This feature request is for the Jabber plug-in to allow for users to turn off this auto-authorization behavior so that users that want to add the Hudson Jabber user will need to be screened and authorized through Gmail's interface. This is a security issue because if any gchat user can add Hudson as a buddy then they will be able to control the build process without any trouble.