<?php

namespace Customize\Entity;

use Doctrine\ORM\Mapping as ORM;
use Eccube\Annotation\EntityExtension;
use Plugin\Event\Entity\Event;

/**
 * @EntityExtension("Eccube\Entity\Product")
 */
trait ProductTrait {
    /**
     * @ORM\ManyToOne(targetEntity="Plugin\Event\Entity\Config", inversedBy="products")
     */
    public $event;

    public function getEvent() {
        return $this->event;
    }

    public function setEvent(Event $event) {
        $this->event = $event;

        return $this;
    }
}

PHP Fatal error:  Trait "Customize\Entity\ProductTrait" not found in /var/www/html/app/proxy/entity/src/Eccube/Entity/Product.php on line 30
Symfony\Component\ErrorHandler\Error\ClassNotFoundError^ {#25
  #message: """
    Attempted to load trait "ProductTrait" from namespace "Customize\Entity".\n
    Did you forget a "use" statement for another namespace?
    """
  #code: 0
  #file: "./app/proxy/entity/src/Eccube/Entity/Product.php"
  #line: 30
}

namespace Eccube\Entity;

use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;
use Plugin\Event\Entity\Event;


    /**
     * Product
     *
     * @ORM\Table(name="dtb_product")
     * @ORM\InheritanceType("SINGLE_TABLE")
     * @ORM\DiscriminatorColumn(name="discriminator_type", type="string", length=255)
     * @ORM\HasLifecycleCallbacks()
     * @ORM\Entity(repositoryClass="Eccube\Repository\ProductRepository")
     */
    class Product extends \Eccube\Entity\AbstractEntity
    {
    use \Customize\Entity\ProductTrait;