pocketmine\scheduler\AsyncTask::setGarbage PHP Method

    public function setGarbage()
    {
        $this->isGarbage = true;
    }

 private function removeTask(AsyncTask $task, $force = false)
 {
     $task->setGarbage();
     if (isset($this->taskWorkers[$task->getTaskId()])) {
         if (!$force and ($task->isRunning() or !$task->isGarbage())) {
             return;
         }
         $this->workerUsage[$this->taskWorkers[$task->getTaskId()]]--;
     }
     unset($this->tasks[$task->getTaskId()]);
     unset($this->taskWorkers[$task->getTaskId()]);
     $task->cleanObject();
 }