protected function isAddingAllowed(EnvironmentInterface $environment)
    {
        $inputProvider = $environment->getInputProvider();

        // No manual sorting property defined, no need to add it to the clipboard.
        // Or we already have an after or into attribute, a handler can pick it up.
        return (!ViewHelpers::getManualSortingProperty($environment)
                || $inputProvider->hasParameter('after')
                || $inputProvider->hasParameter('into')
        );
    }