public function getRESTAvailableValues()
 {
     $type = $this->getBind()->getType();
     if ($type === Tracker_FormElement_Field_List_Bind_Users::TYPE) {
         return array('resource' => array('type' => 'users', 'uri' => 'users/?query='));
     }
     if ($type === Tracker_FormElement_Field_List_Bind_Ugroups::TYPE) {
         $class_user_representation = '\\Tuleap\\Project\\REST\\UserGroupRepresentation';
         $ugroup_manager = new UGroupManager();
         $project = $this->getTracker()->getProject();
         $user_groups = $ugroup_manager->getUGroups($project);
         $values = array();
         foreach ($user_groups as $ugroup) {
             $ugroup_representation = new $class_user_representation();
             $ugroup_representation->build($project->getID(), $ugroup);
             $values[] = $ugroup_representation;
         }
         return $values;
     }
     return parent::getRESTAvailableValues();
 }