func (r *HALResource) HypermediaRels(rels Relations) {
	if r.Links == nil {
		return
	}
	for name, link := range r.Links {
		rels[name] = link.Href
	}
}
HypermediaRels implements the HypermediaResource interface by getting the
Relations from the Links property.
package hypermedia
import (
	"net/url"
)
type HALResource struct {
	Links Links `json:"_links"`
	rels  Relations
}