public function isEmpty($propertyName)
    {
        if (!$this->classSchema->isMultiValuedProperty($propertyName)) {
            throw new InvalidQueryException('Property "' . $propertyName . '" must be multi-valued', 1276853547);
        }
        return $this->qomFactory->comparison(
            $this->qomFactory->propertyValue($propertyName, '_entity'),
            QueryInterface::OPERATOR_IS_EMPTY
        );
    }