+ /**
+ * @ORM\ManyToMany(targetEntity="Wallabag\GroupBundle\Entity\Group", inversedBy="users", cascade={"persist"})
+ * @ORM\JoinTable(name="user_group",
+ * joinColumns={@ORM\JoinColumn(name="user_id", referencedColumnName="id")},
+ * inverseJoinColumns={@ORM\JoinColumn(name="group_id", referencedColumnName="id")}
+ * )
+ */
+ protected $groups;
+