public function toTree( core_kernel_classes_Class $clazz, array $options = array())
    {
        $returnValue = array();

    	$users = $this->getAllUsers(array('order' => GenerisRdf::PROPERTY_USER_LOGIN));
		foreach($users as $user){
			$login = (string) $user->getOnePropertyValue(new core_kernel_classes_Property(GenerisRdf::PROPERTY_USER_LOGIN));
			$returnValue[] = array(
					'data' 	=> tao_helpers_Display::textCutter($login, 16),
					'attributes' => array(
						'id' => tao_helpers_Uri::encode($user->getUri()),
						'class' => 'node-instance'
					)
				);

		}

        return (array) $returnValue;
    }