/**
  * Clone Message Signers.
  *
  * @see Swift_Mime_SimpleMimeEntity::__clone()
  */
 public function __clone()
 {
     parent::__clone();
     foreach ($this->bodySigners as $key => $bodySigner) {
         $this->bodySigners[$key] = clone $bodySigner;
     }
     foreach ($this->headerSigners as $key => $headerSigner) {
         $this->headerSigners[$key] = clone $headerSigner;
     }
 }