/**
  * @param UpdateTaskMetadata $command
  * @throws Exception\TaskNotFound
  */
 public function handle(UpdateTaskMetadata $command)
 {
     $task = $this->taskCollection->get($command->taskId());
     if (is_null($task)) {
         throw TaskNotFound::withId($command->taskId());
     }
     $task->updateMetadata($command->metadata());
 }