property code style extensions

Mailer.php

@@ -79,6 +79,7 @@ class Mailer extends BaseMailer
      * @var string message default class name.
      */
     public $messageClass = 'yii\swiftmailer\Message';
+
     /**
      * @var \Swift_Mailer Swift mailer instance.
      */
@@ -88,6 +89,7 @@ class Mailer extends BaseMailer
      */
     private $_transport = [];
 
+
     /**
      * @return array|\Swift_Mailer Swift mailer instance or array configuration.
      */

Message.php

@@ -29,6 +29,7 @@ class Message extends BaseMessage
      */
     private $_swiftMessage;
 
+
     /**
      * @return \Swift_Message Swift message instance.
      */