minor #35081 [Notifier] Add more specific types at documentation leve…

…l when php engine can't (Philippe Segatori)

This PR was squashed before being merged into the 5.0 branch (closes #35081).

Discussion
----------

[Notifier] Add more specific types at documentation level when php engine can't

| Q             | A
| ------------- | ---
| Branch?       | 5.0 <!-- see below -->
| Bug fix?      | no
| New feature?  | no <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | Fix #35078  <!-- prefix each issue number with "Fix #", if any -->
| License       | MIT
| Doc PR        | . <!-- required for new features -->

This an example of the proposal made in #35078 to document a narrower type when php type declaration cannot.

Commits
-------

b9931f5 [Notifier] Add more specific types at documentation level when php engine can't

src/Symfony/Component/Notifier/Bridge/Nexmo/NexmoTransportFactory.php

@@ -23,6 +23,9 @@
  */
 final class NexmoTransportFactory extends AbstractTransportFactory
 {
+    /**
+     * @return NexmoTransport
+     */
     public function create(Dsn $dsn): TransportInterface
     {
         $scheme = $dsn->getScheme();

src/Symfony/Component/Notifier/Bridge/Slack/SlackTransportFactory.php

@@ -23,6 +23,9 @@
  */
 final class SlackTransportFactory extends AbstractTransportFactory
 {
+    /**
+     * @return SlackTransport
+     */
     public function create(Dsn $dsn): TransportInterface
     {
         $scheme = $dsn->getScheme();

src/Symfony/Component/Notifier/Bridge/Telegram/TelegramTransportFactory.php

@@ -24,6 +24,9 @@
  */
 final class TelegramTransportFactory extends AbstractTransportFactory
 {
+    /**
+     * @return TelegramTransport
+     */
     public function create(Dsn $dsn): TransportInterface
     {
         $scheme = $dsn->getScheme();

src/Symfony/Component/Notifier/Bridge/Twilio/TwilioTransportFactory.php

@@ -23,6 +23,9 @@
  */
 final class TwilioTransportFactory extends AbstractTransportFactory
 {
+    /**
+     * @return TwilioTransport
+     */
     public function create(Dsn $dsn): TransportInterface
     {
         $scheme = $dsn->getScheme();

src/Symfony/Component/Notifier/Message/SmsMessage.php

@@ -58,7 +58,7 @@ public function getPhone(): string
         return $this->phone;
     }
 
-    public function getRecipientId(): ?string
+    public function getRecipientId(): string
     {
         return $this->phone;
     }

src/Symfony/Component/Notifier/Transport/NullTransportFactory.php

@@ -20,6 +20,9 @@
  */
 final class NullTransportFactory extends AbstractTransportFactory
 {
+    /**
+     * @return NullTransport
+     */
     public function create(Dsn $dsn): TransportInterface
     {
         if ('null' === $dsn->getScheme()) {