src/Core/OAuth/OAuth2/OAuth2AccessToken.php
public function getAccessToken(){
      if(isset($this->accessTokenKey) && !empty($this->accessTokenKey))  return $this->accessTokenKey;
      else throw new SdkException("The OAuth 2 Access Token is not set in the Access Token Object.");
    }
public function getAccessToken(){
      if(isset($this->accessTokenKey) && !empty($this->accessTokenKey))  return $this->accessTokenKey;
      else throw new SdkException("The OAuth 2 Access Token is not set in the Access Token Object.");
    }
Return the access Token
@return String