Add null types

Author: benr77

tests/Functional/Entity/TaskExecutionRepositoryTest.php

@@ -187,7 +187,7 @@ public function testFindScheduledSkipped()
      *
      * @return TaskExecutionInterface
      */
-    private function save(TaskInterface $task = null, \DateTimeImmutable $scheduleTime = null, $status = TaskStatus::PLANNED)
+    private function save(?TaskInterface $task = null, ?\DateTimeImmutable $scheduleTime = null, $status = TaskStatus::PLANNED)
     {
         if (!$scheduleTime) {
             $scheduleTime = new \DateTimeImmutable();