/**
* Retrieve the object's configuration container, or one of its entry.
*
* If the object has no existing config, create one.
*
* If a key is provided, return the configuration key value instead of the full object.
*
* @param string $key Optional. If provided, the config key value will be returned, instead of the full object.
* @see self::create_config()
* @return ConfigInterface
*/
public function config($key = null)
{
if ($this->config === null) {
$this->config = $this->createConfig();
}
if ($key !== null) {
return $this->config->get($key);
} else {
return $this->config;
}
}
