void process(gsl::span< const Digit > digits, gsl::span< const DigROFRecord > digitROFs, std::vector< o2::trk::Cluster > &clusters, std::vector< unsigned char > &patterns, std::vector< o2::trk::ROFRecord > &clusterROFs, const ConstDigitTruth *digitLabels=nullptr, ClusterTruth *clusterLabels=nullptr) override