Hydration down not work for annotation "@ReferenceMany"

<?php

/**
 * @Document(db="DB", collection="Users")
 */
class User
{
    /**
     * @Id
     */
    public $id;
    /**
     * @String
     */
    public $name;
    /**
     * @String
     */
    public $password;
    /**
     * @String
     */
    public $email;
        /**
     * @ReferenceMany(targetDocument="Group")
     */
    public $groups = array();
}
?>

<?php

/**
 * @Document(db="MCI", collection="Groups")
 */
class Group
{
    /**
     * @Id
     */
    public $id;
    /**
     * @String
     */
    public $name;
    /**
     * @String
     */
    public $role_name;

}
?>

 $obj = $this->dm->findOne("User",("name" => "Flavio"));