Done. StateServers is omitted on empty.
>
> In cmd/juju/switch.go:
>
> >  `
> >
> > +type EnvInfo struct {
> > +	Username            string   `yaml:"user-name" json:"user-name"`
> > +	EnvironName         string   `yaml:"environ-name" json:"environ-name"`
> > +	PreviousEnvironName string   `yaml:"previous-environ-name,omitempty" json:"previous-environ-name,omitempty"`
> > +	StateServers        []string `json:"state-servers" yaml:"state-servers"`
>
> I think the json and yaml for this should include omitempty, so they 
> can be optionally added
>
> —
> Reply to this email directly or view it on GitHub 
> <https://github.com/juju/juju/pull/20/files#r13420040>.
>