/**
* Create a new CommandEvent for $source with $command.
* @param Swift_Transport $source
* @param string $command
* @param array $successCodes
*/
public function __construct(Swift_Transport $source, $command, $successCodes = array())
{
parent::__construct($source);
$this->_command = $command;
$this->_successCodes = $successCodes;
}