HttpClient::prepareMultipart

protected function prepareMultipart($postData)
{
	if (is_array($postData))
	{
		try
		{
			$data = new HttpMultipartStream($postData);
			$this->setHeader('Content-type', 'multipart/form-data; boundary=' . $data->getBoundary());

			return $data;
		}
		catch (ArgumentException $e)
		{
			$this->addError('MULTIPART', $e->getMessage(), true);
			return false;
		}
	}

	return $postData;
}