/**
     * @return string
     */
    private function generateResponseFragment($indent = '')
    {
        $body = '';
        $responseClass = $this->operationDefinition->getResponseClass();
        $responseFactory = $this->operationDefinition->getResponseFactory();
        $responseCallable = $this->operationDefinition->getResponseCallable();
        if ($responseCallable) {
            throw new \Exception("This is not implemented yet.");
        } else {
            if (true) {
                //Hard-code this for now.
                $body .= <<<END
{$indent}\$instance = \$this->api->instantiateResult(\$response, \$this);

{$indent}return \$instance;
END;
            } else {
                if ($responseFactory) {
                    //Response is turned by $responseFactory into $responseClass
                    $body .= <<<END
{$indent}\$instance = \\{$responseClass}::createFromResponse(\$response, \$this);

{$indent}return \$instance;
END;
                } else {
                    if ($responseClass) {
                        //Response is turned into $responseClass by a static method on that class
                        $body .= <<<END
{$indent}\$instance = \\{$responseClass}::createFromResponse(\$response, \$this);

{$indent}return \$instance;
END;
                    } else {
                        //TODO - should this be like this or just return $response?
                        //No hydrating of data done.
                        $body .= $indent . 'return $response->getBody();';
                    }
                }
            }
        }
        return $body;
    }