code: func (d Deployment) MarshalJSON() ([]byte, error) {
  	type Droplet struct {
  		GUID string `json:"guid,omitempty"`
  	}
  
  	var ccDeployment struct {
  		Droplet       *Droplet      `json:"droplet,omitempty"`
  		Relationships Relationships `json:"relationships,omitempty"`
  	}
  
  	if d.DropletGUID != "" {
  		ccDeployment.Droplet = &Droplet{d.DropletGUID}
  	}
  
  	ccDeployment.Relationships = d.Relationships
  
  	return json.Marshal(ccDeployment)
  }
docs: // MarshalJSON converts a Deployment into a Cloud Controller Deployment.