public function exec($resourceUrl, $postString = '')
{
$url = UrlBuilder::buildApiUrl($resourceUrl);
$headers = $this->getHttpHeaders();
$postString = $this->filePathToUpload ? $this->postFileData : $postString;
$result = $this->httpClient->execute($url, $postString, $headers);
$this->filePathToUpload = null;
return $result;
}