Merge branch '6.1' into 6.2

* 6.1:
  Correct time type return
  Fix `notifier.flash_message_importance_mapper` service definition
  Fix a typo
  Reword
  add tip about listener priority to mailer.rst

Author: javiereguiluz

components/phpunit_bridge.rst

@@ -545,7 +545,7 @@ specified.
 Other functions with an optional timestamp parameter that defaults to ``time()``
 will still use the system time instead of the mocked time. This means that you
 may need to change some code in your tests. For example, instead of ``new DateTime()``,
-you should use ``DateTime::createFromFormat('U', time())`` to use the mocked
+you should use ``DateTime::createFromFormat('U', (string) time())`` to use the mocked
 ``time()`` function.
 
 To use the ``ClockMock`` class in your test, add the ``@group time-sensitive``

mailer.rst

@@ -956,6 +956,8 @@ This makes use of the :ref:`styles Twig namespace <mailer-css-namespace>` we cre
 earlier. You could, for example, `download the foundation-emails.css file`_
 directly from GitHub and save it in ``assets/styles``.
 
+.. _signing-and-encrypting-messages:
+
 Signing and Encrypting Messages
 -------------------------------
 
@@ -1429,6 +1431,13 @@ is sent::
         // do something with the message
     }
 
+.. tip::
+
+    When using a ``MessageEvent`` listener to
+    :doc:`sign the email contents <signing-and-encrypting-messages>`, run it as
+    late as possible (e.g. setting a negative priority for it) so the email
+    contents are not set or modified after signing them.
+
 Execute this command to find out which listeners are registered for this event
 and their priorities:
 
@@ -1489,7 +1498,7 @@ FailedMessageEvent
     {
         // e.g you can get more information on this error when sending an email
         $event->getError();
-        
+
         // do something with the message
     }
 

notifier.rst

@@ -729,7 +729,8 @@ typical alert levels, which you can implement immediately using:
 
         # config/services.yaml
         services:
-            notifier.flash_message_importance_mapper: Symfony\Component\Notifier\FlashMessage\BootstrapFlashMessageImportanceMapper
+            notifier.flash_message_importance_mapper: 
+                class: Symfony\Component\Notifier\FlashMessage\BootstrapFlashMessageImportanceMapper
 
     .. code-block:: xml