protected function configApi(ConfigXML $config)
    {
        $this->config(static::TOOL_CANVAS_API, $config->toArray('/config/canvas')[0]);
        if (empty($this->config(static::TOOL_CANVAS_API))) {
            throw new ConfigurationException(
                'Canvas API credentials must be provided',
                ConfigurationException::CANVAS_API_MISSING
            );
        }
        $this->log('Canvas API credentials configured');
    }