minor symfony#42738 [Console] Fix optional before mandatory parameters (derrabus)

This PR was merged into the 4.4 branch. Discussion ---------- [Console] Fix optional before mandatory parameters | Q | A | ------------- | --- | Branch? | 4.4 | Bug fix? | yes | New feature? | no | Deprecations? | no | Tickets | symfony#42635 (comment) | License | MIT | Doc PR | N/A Commits ------- aec3021 Fix optional before mandatory parameters

Author: chalasr

src/Symfony/Component/Console/Event/ConsoleEvent.php

@@ -28,7 +28,7 @@ class ConsoleEvent extends Event
  private $input;
  private $output;
 
- public function __construct(Command $command = null, InputInterface $input, OutputInterface $output)
+ public function __construct(?Command $command, InputInterface $input, OutputInterface $output)
  {
  $this->command = $command;
  $this->input = $input;