code: func (r *Subresource) HasChange(key string) bool {
  	o, n := r.GetChange(key)
  	return !reflect.DeepEqual(o, n)
  }
docs: // HasChange checks to see if there has been a change in the resource data
  // since the last update.
  //
  // Note that this operation may only be useful during update operations,
  // depending on subresource-specific workflow.