Cannot get the User, from TokenStorage

SquareCropApprovalRequiredSubscriber.php

<?php
namespace ContestEngineBundle\Service\EventSubscriber;


use Doctrine\Common\Annotations\Reader;
use Doctrine\Common\EventSubscriber;
use Doctrine\Common\Persistence\Event\LifecycleEventArgs;
use Symfony\Component\Security\Core\Authentication\Token\Storage\TokenStorageInterface;

class SquareCropApprovalRequiredSubscriber implements EventSubscriber
{
    private $token_storage;
    private $user;
    private $reader;

    public function getSubscribedEvents()
    {
        return array(
            'postLoad',
        );
    }

    public function __construct(TokenStorageInterface $token_storage, Reader $reader)
    {
        $this->token_storage = $token_storage;
        $this->reader        = $reader;
    }


    public function postLoad(LifecycleEventArgs $args)
    {
        $entity = $args->getObject();
      
      // Issue,
      // $this->token_storage->getToken == null.
        $user = $this->token_storage->getToken()->getUser();
      
    }


}