This is a fork of the package: cpliakas/solarium-luke, but since it seems inactive, I'm maintaining a version here. The namespaces are still the same, so the only thing you have to do to migrate to this package, is replacing the installation like so:
composer remove cpliakas/solarium-luke \
&& composer require roelofjan-elsinga/solarium-lukeA Luke request handler to Solarium.
This package currently supports Solarium 5.x.
use Solarium\Client;
use Solarium\QueryType\Luke\Query;
$client = new Client();
$client->registerQueryType(Query::QUERY_LUKE, Query::class);
$luke = $client->createQuery(Query::QUERY_LUKE);
$data = $client->execute($luke);
print 'Top terms: ';
var_dump($data->getTopTerms());
print PHP_EOL;