refreshToken is blank

refreshToken is blank

When running the following, I get a response and the zcrm_oauthtokens.txt file is saved, but both only have an access token but the refresh token is blank.

  1. $configuration = [
  2.       "client_id" => $client_id,
  3.       "client_secret" => $client_secret,
  4.       "redirect_uri" => $redirect_uri,
  5.       "currentUserEmail" => $currentUserEmail,
  6.       "token_persistence_path" => $token_persistence_path
  7. ];
  8. ZCRMRestClient::initialize($configuration);

  10. try {
  11.       $oAuthClient = \zcrmsdk\oauth\ZohoOAuth::getClientInstance();
  12.       $oAuthTokens = $oAuthClient->generateAccessToken($grantToken);
  13.       print_r($oAuthTokens);
  14. } catch (Error $e) {
  15.       echo $e->getMessage();
  16. }

Here's the print_r() result I get:
zcrmsdk\oauth\utility\ZohoOAuthTokens Object ( [refreshToken:zcrmsdk\oauth\utility\ZohoOAuthTokens:private] => [accessToken:zcrmsdk\oauth\utility\ZohoOAuthTokens:private] => 1000.blahblah [expiryTime:zcrmsdk\oauth\utility\ZohoOAuthTokens:private] => 1584131163031 [userEmailId:zcrmsdk\oauth\utility\ZohoOAuthTokens:private] => )

It does not return a refreshToken. Same in the zcrm_oauthtokens.txt file.