code: func (client *Client) SetApplicationDroplet(appGUID string, dropletGUID string) (Relationship, Warnings, error) {
  	relationship := Relationship{GUID: dropletGUID}
  	bodyBytes, err := json.Marshal(relationship)
  	if err != nil {
  		return Relationship{}, nil, err
  	}
  
  	request, err := client.newHTTPRequest(requestOptions{
  		RequestName: internal.PatchApplicationCurrentDropletRequest,
  		URIParams:   map[string]string{"app_guid": appGUID},
  		Body:        bytes.NewReader(bodyBytes),
  	})
  	if err != nil {
  		return Relationship{}, nil, err
  	}
  
  	var responseRelationship Relationship
  	response := cloudcontroller.Response{
  		DecodeJSONResponseInto: &responseRelationship,
  	}
  	err = client.connection.Make(request, &response)
  
  	return responseRelationship, response.Warnings, err
  }
docs: // SetApplicationDroplet sets the specified droplet on the given application.