src/Core/OAuth/OAuth2/OAuth2LoginHelper.php
public function getClientSecret(){
        if(isset($this->clientSecret) && !empty($this->clientSecret)){
            return (String)$this->clientSecret;
        }else{
          throw new SdkException("Can't get OAuth 2 Client Secret. It is not set.");
        }
    }
public function getClientSecret(){
        if(isset($this->clientSecret) && !empty($this->clientSecret)){
            return (String)$this->clientSecret;
        }else{
          throw new SdkException("Can't get OAuth 2 Client Secret. It is not set.");
        }
    }
Return the Client Secret for the App
@return String   The clientSecret