code: func (client *Client) GetServiceInstance(serviceInstanceGUID string) (ServiceInstance, Warnings, error) {
  	request, err := client.newHTTPRequest(requestOptions{
  		RequestName: internal.GetServiceInstanceRequest,
  		URIParams:   Params{"service_instance_guid": serviceInstanceGUID},
  	})
  	if err != nil {
  		return ServiceInstance{}, nil, err
  	}
  
  	var serviceInstance ServiceInstance
  	response := cloudcontroller.Response{
  		DecodeJSONResponseInto: &serviceInstance,
  	}
  
  	err = client.connection.Make(request, &response)
  	return serviceInstance, response.Warnings, err
  }
docs: // GetServiceInstance returns the service instance with the given GUID. This
  // service can be either a managed or user provided.