Comment 7 for bug 1341096

I think it is a bug of parsing mechanism in neutronclient.

Honestly speaking, this kind of parsing is a technical debt in neutronclient. A mechinism of unknown arguments is useful for extension, but we received many bug reports around this. I am not sure we should keep this when we move to openstackclient. At now, I don't have a plan to propose to support unknown arguments for openstackclient and we should have explicit arguments for updateable fields.