AdWordsUser::GetDeveloperToken PHP Method

    public function GetDeveloperToken()
    {
        return $this->GetHeaderValue('developerToken');
    }

 /**
  * Gets the HTTP headers for the report download request.
  * @param AdWordsUser $user the AdWordsUser to get credentials from
  * @param string $url the URL the request will be made to
  * @param array $options the options for the download
  * @return array and array of strings, which are header names and values
  */
 private static function GetHeaders($user, $url, array $options = NULL)
 {
     $headers = array();
     $version = !empty($options['version']) ? $options['version'] : $user->GetDefaultVersion();
     // Authorization.
     $authHeader = NULL;
     $oAuth2Info = $user->GetOAuth2Info();
     $oAuth2Handler = $user->GetOAuth2Handler();
     if (!empty($oAuth2Info)) {
         $oAuth2Info = $oAuth2Handler->GetOrRefreshAccessToken($oAuth2Info);
         $user->SetOAuth2Info($oAuth2Info);
         $authHeader = $oAuth2Handler->FormatCredentialsForHeader($oAuth2Info);
     } else {
         throw new ServiceException('OAuth 2.0 authentication is required.');
     }
     $headers['Authorization'] = $authHeader;
     // Developer token.
     $headers['developerToken'] = $user->GetDeveloperToken();
     // Target client.
     $clientCustomerId = $user->GetClientCustomerId();
     if (isset($clientCustomerId)) {
         $headers['clientCustomerId'] = $clientCustomerId;
     } else {
         throw new ReportDownloadException('The client customer ID must be ' . 'specified for report downloads.');
     }
     // Flags.
     if (isset($options['returnMoneyInMicros'])) {
         DeprecationUtils::CheckUsingReturnMoneyInMicrosWithUnsupportedVersion(self::FINAL_RETURN_MONEY_IN_MICROS_VERSION, $version);
         $headers['returnMoneyInMicros'] = $options['returnMoneyInMicros'] ? 'true' : 'false';
     }
     return $headers;
 }