protected function getFieldNames(Criterion $criterion)
    {
        $fieldDefinitionIdentifier = $criterion->target;
        $fieldMap = $this->contentTypeHandler->getSearchableFieldMap();
        $fieldNames = [];

        foreach ($fieldMap as $contentTypeIdentifier => $fieldIdentifierMap) {
            if (!isset($fieldIdentifierMap[$fieldDefinitionIdentifier])) {
                continue;
            }

            $fieldNames[] = $this->fieldNameGenerator->getTypedName(
                $this->fieldNameGenerator->getName(
                    'is_empty',
                    $fieldDefinitionIdentifier,
                    $contentTypeIdentifier
                ),
                new BooleanField()
            );
        }

        return $fieldNames;
    }