Make EmailMessage & SmsMessage transport nullable

Author: Olivier Dolbeau

Message/EmailMessage.php

@@ -97,11 +97,14 @@ public function getOptions(): ?MessageOptionsInterface
     /**
      * @return $this
      */
-    public function transport(string $transport): self
+    public function transport(?string $transport): self
     {
         if (!$this->message instanceof Email) {
             throw new LogicException('Cannot set a Transport on a RawMessage instance.');
         }
+        if (null === $transport) {
+            return $this;
+        }
 
         $this->message->getHeaders()->addTextHeader('X-Transport', $transport);
 

Message/SmsMessage.php

@@ -81,7 +81,7 @@ public function getSubject(): string
     /**
      * @return $this
      */
-    public function transport(string $transport): self
+    public function transport(?string $transport): self
     {
         $this->transport = $transport;