class QueryFactory

class QueryFactory implements QueryFactoryInterface {
    
    /**
     * The key value factory.
     *
     * @var \Drupal\Core\KeyValueStore\KeyValueFactoryInterface
     */
    protected $keyValueFactory;
    
    /**
     * The namespace of this class, the parent class etc.
     *
     * @var array
     */
    protected $namespaces;
    
    /**
     * Constructs a QueryFactory object.
     */
    public function __construct(KeyValueFactoryInterface $key_value_factory) {
        $this->keyValueFactory = $key_value_factory;
        $this->namespaces = Query::getNamespaces($this);
    }
    
    /**
     * {@inheritdoc}
     */
    public function get(EntityTypeInterface $entity_type, $conjunction) {
        return new Query($entity_type, $conjunction, $this->namespaces, $this->keyValueFactory);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getAggregate(EntityTypeInterface $entity_type, $conjunction) {
        throw new QueryException('Aggregation over key-value entity storage is not supported');
    }

}