Right now our broker and backend URL default values are not using Girder's default setting mechanism, so downstreams of this plugin can't easily hook into the setting mechanisms to use the default, they're forced to duplicate it.
I realize the reason for this is to handle the fact that this setting is often saved to the database with a value of the empty string. I don't know of any clever workaround for that at this point.
Right now our broker and backend URL default values are not using Girder's default setting mechanism, so downstreams of this plugin can't easily hook into the setting mechanisms to use the default, they're forced to duplicate it.