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
        );
    }
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
        );
    }
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 ) ; }
Returns an "isEmpty" criterion used for matching objects against a query.
It matches if the multivalued property contains no values or is NULL.

@param string $propertyName The name of the multivalued property to check
@return boolean
@throws InvalidQueryException if used on a single-valued property
@api
Returns an isEmpty criterion used for matching objects against a query . It matches if the multivalued property contains no values or is NULL .