/**
  * @return Response
  */
 public function requestAccessToken()
 {
     $this->prepareRequest();
     $this->request->setUri($this->configuration->getBaseUri() . self::TOKEN_ENDPOINT);
     $this->request->setMethod('POST');
     $payload = $this->httpClient->buildQuery(array('client_id' => $this->configuration->getClientId(), 'client_secret' => $this->configuration->getClientSecret(), 'grant_type' => $this->configuration->getGrantType(), 'username' => $this->configuration->getUsername(), 'password' => $this->configuration->getPassword(), 'company' => $this->configuration->getCompany()));
     $this->request->setPayload($payload);
     return $this->httpClient->send($this->request);
 }