Symfony and Doctrine ORM – Many to many bidirectional relation

The classes below illustrate a many to many bidirectional relation with Doctrine ORM, Symfony3 and FOSUserBundle.

Entity User

<?php
// src/AppBundle/Entity/User.php

namespace AppBundle\Entity;

use FOS\UserBundle\Model\User as BaseUser;
use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;

/**
 * @ORM\Entity
 * @ORM\Table(name="fos_user")
 */
class User extends BaseUser
{
    /**
     * @ORM\Id
     * @ORM\Column(type="integer")
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    protected $id;

    /**
     * @ORM\ManyToMany(targetEntity="UserGroup", inversedBy="users")
     * @ORM\JoinColumn(name="usergroup_id", referencedColumnName="id")
     */
    private $usergroups;

    public function __construct()
    {
        parent::__construct();
        $this->usergroups = new ArrayCollection();
    }
}

Entity UserGroup

<?php

namespace AppBundle\Entity;

use Doctrine\ORM\Mapping as ORM;
use Doctrine\Common\Collections\ArrayCollection;

/**
 * UserGroup
 *
 * @ORM\Table(name="user_group")
 * @ORM\Entity(repositoryClass="AppBundle\Repository\UserGroupRepository")
 */
class UserGroup
{
    /**
     * @var int
     *
     * @ORM\Column(name="id", type="integer")
     * @ORM\Id
     * @ORM\GeneratedValue(strategy="AUTO")
     */
    private $id;

    /**
     * @var string
     *
     * @ORM\Column(name="name", type="string", length=255, unique=true)
     */
    private $name;

    /**
     * @var string
     *
     * @ORM\Column(name="description", type="text", nullable=true)
     */
    private $description;

    /**
     * @ORM\ManyToMany(targetEntity="User", mappedBy="usergroups")
     */
    private $users;

    public function __construct()
    {
        $this->users = new ArrayCollection();
    }

    /**
     * Get id
     *
     * @return int
     */
    public function getId()
    {
        return $this->id;
    }

    /**
     * Set name
     *
     * @param string $name
     *
     * @return UserGroup
     */
    public function setName($name)
    {
        $this->name = $name;

        return $this;
    }

    /**
     * Get name
     *
     * @return string
     */
    public function getName()
    {
        return $this->name;
    }

    /**
     * Set description
     *
     * @param string $description
     *
     * @return UserGroup
     */
    public function setDescription($description)
    {
        $this->description = $description;

        return $this;
    }

    /**
     * Get description
     *
     * @return string
     */
    public function getDescription()
    {
        return $this->description;
    }
}