Association mapping 'One-To-Many, Self-referencing' with cascade and removes fk onDelete=restrict

<?php
/** @Table(name="category") */
class Category
{
    /**
     * @Id
     * @Column(name="id")
     */
    public $id;

    /**
     * @OneToMany(targetEntity="Category", mappedBy="parent", cascade={"remove"})
     */
    public $children;

    /**
     * @ManyToOne(targetEntity="Category", inversedBy="children")
     * @JoinColumn(name="parent_id", referencedColumnName="id")
     */
    public $parent;

    public function __construct() {
        $this->children = new \Doctrine\Common\Collections\ArrayCollection();
    }
}
?>

CREATE TABLE `category` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `parent_id` int(10) unsigned DEFAULT NULL,
  `name` varchar(50) NOT NULL,
  PRIMARY KEY (`id`),
  KEY `fk_id_parent_id` (`parent_id`),
  CONSTRAINT `fk_id_parent_id` FOREIGN KEY (`parent_id`) REFERENCES `category` (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=18 DEFAULT CHARSET=utf8 ROW_FORMAT=DYNAMIC